In the second annual paidContent 50 list, we rank  the most-successful media companies in the world according to digital content revenue. On that list, you’ll find companies like Bloomberg and Thomson Reuters. But, in this post, I want to look at what I think are the most interesting media companies, new and old, and what they can tell us about where the opportunities lie in the future.

These are not the most financially successful media companies, or the most influential, and I’m not recommending that everyone emulate them. I’m simply arguing that they are interesting in some way — either because they are trying something new, or because they are zigging while everyone else is zagging. With that in mind, here are my choices and why I think they are worth paying attention to, in no specific order:

Twitter

We’ve been arguing for some time that Twitter is a media entity, and there is increasing evidence to support that argument, including the company’s move into curated editorial offerings such as its weekly email (which it launched after acquiring Summify) as well as sports-related news hubs like the one it is planning to launch in partnership with NBC for the Olympics. One of the most interesting things about Twitter is that it is trying to create what amounts to a multibillion-dollar advertising-supported media company using other peoples’ content, especially with new features such as expanded tweets — which embed additional content inside Twitter’s apps and website. And now there are rumors that Twitter is looking to help create TV-style programming that will appear within and be promoted throughout the network. But can the company do these things without diluting what many users see as its core value as a real-time information utility?

Amazon

The world’s biggest online-only retailer helped to revolutionize the media industry by disrupting the book-retailing business with its website, but then it went a step further with the Kindle e-book reader — which has created a platform for publishing of all kinds, whether it’s magazine-style feature stories, or self-published books that have made some early adopters such as Amanda Hocking into multimillionaires. In the process, the company has disintermediated not just book publishers but agents and publicists and almost every other aspect of the traditional publishing industry, and the virulence of the reaction to the e-book pricing deal that publishers signed with Apple (as an attempt to stave off Amazon’s growing market power) is another indicator of just how high the stakes are. It’s also more evidence that the only company to have revolutionized mobile media as much as Apple is Amazon.

BuzzFeed

For many people, the “viral content” site may still be associated with photo galleries of funny pictures and animated GIFs of various internet memes, but BuzzFeed has been making some ambitious moves to become a full-fledged media player — and regardless of its reputation as a time-waster, it’s worth paying attention to. In a recent internal memo to employees, co-founder and CEO Jonah Peretti talked about how the company wants to create the first truly digital-native media company (although The Huffington Post arguably also fits that bill), one that understands how content works online and what users want. BuzzFeed is currently trying to take the same principles that apply to cat pictures and figure out how to use them for more serious topics such as world politics, but it remains to be seen whether readers will want such a combination.

The Guardian

It may seem odd to nominate an old-media company like a newspaper as one of the most interesting media companies, but The Guardian fits into the “zigging while everyone else is zagging” category. With almost every other major newspaper either implementing or contemplating a paywall (apart from the Washington Post), The Guardian has remained steadfastly opposed to paywalls. Although editor-in-chief Alan Rusbridger has mused about offering some form of subscription content, it’s clear that The Guardian is more interested in pursuing what Rusbridger calls “open journalism,” which involves bringing readers into the process in as many different ways as possible. The Guardian has a bit more room than other newspapers to experiment because it is owned by a trust. It’s a little early to call open journalism a recipe for success, since the newspaper just announced a loss of $70 million. But it is a fascinating experiment nevertheless (please see the disclosure statement below).

Gawker

Almost every online media company struggles to deal with the comments that readers leave on their content — they know that having them is important, but comment sections are also often filled with bile and invective rather than insight. In one of the first real efforts at re-thinking how comments function, Gawker founder Nick Denton introduced a new system at his online properties that turns each commenter into an editor (in the sense that they can choose to respond to or hide any response their comments get) and at the same time encourages them to become a contributing part of the discussion, something Denton says is starting to have an effect. The Gawker founder’s vision is that comments shouldn’t be an afterthought or a second cousin to an online post — they should be the most important part of the impact that post has. Whether Denton’s new system will become a model that other media outlets can duplicate or learn from remains to be seen.

So can a platform owner like Amazon manage to use its control over a device like the Kindle to supplant the entire book-publishing ecosystem? Can The Guardian pursue an “open journalism” approach and make it work financially? Can Twitter turn itself from an information utility into a full-fledged media entity without losing the unique properties that made it desirable in the first place? These are just some of the questions that are raised by the companies in this list — and watching the answers play out over the next year or so should be a fascinating learning opportunity for other media players of all kinds.

Check out the full paidContent 50 list.

Disclosure: Guardian News & Media Ltd., the parent company of the Guardian newspaper, is an investor in the parent company of this blog, Giga Omni Media

But the Mountain View firm’s growth came not from successful expansion into new revenue lines like social or mobile. No, it came from the company’s ability to wring more and more out of its existing core business: advertising. Google, which changed leadership last year to refocus on product innovation, makes almost eight times more from online ads than even the world’s largest advertising agency, WPP.

Changing of the guard

Another individual story that jumps from the list: Apple leapfrogging Yahoo. Yahoo lost a fifth of its revenue in 2011, while Apple piled on another $1.3 billion (30 percent) in digital content sales from new iPad owners, new in-app subscriptions and customers in new countries.

Despite its travails, Yahoo is by no means a dead duck. But we think the open web’s biggest ad-funded portal  has passed the runner-up-to-Google baton to Apple’s device-centric retail ecosystem. We look forward to seeing how Yahoo’s latest CEO, Marissa Mayer, intends to make up ground on Apple and her former employer, Google.

Few on our list have surged quite like the world’s biggest social network.  Facebook revenue more than tripled en route to its IPO, taking it past heavyweights and veterans like News Corp, Amazon, Walt Disney. Not bad for an outfit that, in its S-1 filing, conceded its own advertising model was essentially an experiment.

Trading places

This year’s paidContent 50, for the first time, looks at companies outside the U.S. and in segments not considered last year, like business information and advertising. As a consequence, several U.S. companies fell off this year’s list — including CareerBuilder, ValueClick, WebMD, GameStop, Hulu, the New York Times, Ancestry.com and Demand Media.

This doesn’t necessarily mean that they had a bad year — the New York Times’ digital earnings grew thanks to its new metered fees, Hulu’s content cash almost doubled from subscriptions and heightened ad sales, while Demand  rode out Google’s indexing algorithm change to also earn more than last year.

Meanwhile, Groupon’s daily-deal revenue tripled through the year (allowing it to fall only one spot on our list, to #24), while Time Warner – which used the paidContent 50 to make its first ever company-wide digital content earnings disclosure – would have leaped 13 places if our list continued to focus on U.S. companies (instead, it dropped a few spots).

It came from the east

Indeed, opening the gates to the rest of the world adds some new perspective on the success of some of the largest U.S. digital players. Zynga, for example, suddenly falls 24 places, while Netflix sinks 14 places despite adding about $500,000 in revenue in an error-strewn year. Almost half of our list this year (23 companies) comes from outside the U.S.

China Mobile, the PC50′s top performer from the country with the largest internet population, is capitalizing on a mobile internet boom that, though it has happened later in China than the west, looks more profound. Sales of mobile data content propelled the carrier to #2 on our list.

Another Chinese company, Tencent, #9 on our list, is an internet brand so diverse it defies brief characterisation (though our profile makes an attempt). And South African old-line publisher Naspers is little talked about, but, at #22, you can see what its aggressive strategy of overseas online investments has done for the firm.

 Check out the complete paidContent 50 list here

1. You’ve come a long way, baby

The paidContent 50 collectively are generating $150-billion-a-year in digital revenue. That number is impressive, and shows how far our industry has come in less than 20 years — digital media has never been more relevant or influential.

But it makes up just 16.5 percent of the total revenue of those 50 companies. One reason: Many media companies still have a way to go before becoming truly “digital.” Another: for many companies on the list, content is just a small part of their business.

2. China has become a force in media, too

This year, we included non-U.S. companies in our paidContent 50 list, and Chinese firms were a big beneficary. Asia’s experiencing a smartphone and internet boom (shipments are growing 16 times faster than in the U.S.), and that has created a digital content market with awesome scale, supporting “hyper-growth” in mobile apps. Now that growing chunks of its 1.3 billion people are getting wired, China’s portals, telcos and online games are becoming major players on the global stage.

3. ‘Digital’ becomes more visible as it becomes more meaningful

Our perennial reporting challenge with this list is that many companies refuse to identify “digital revenue” except when it suits them. For instance, CBS happily discloses 17 percent of Simon & Schuster revenue is digital, though doesn’t do the same for other CBS units. But some companies are changing their ways as their digital content sales become more respectable. When it was $20 million, digital revenue for the cable channel Discovery used to be tucked inside “Other.” It has since grown to $109 million, and can be found under “Distribution.”

4. Paid and free pay equally

Skeptics may argue the internet is a land of the free, where publishers will struggle to charge for content. But the content companies on our PC50 list are split almost equally between chargers and non chargers. Also: They may not be sexy but business-information publishers that sell content are making a pretty penny in the migration from B2B print publishing to digital data provision. We estimate Bloomberg, Thomson Reuters, Wolters Kluwer, Dun & Bradstreet, Reed Elsevier and Informa collectively make around $23.5 billion from selling digital content.

5. Ads add up for big companies

Advertising-related content features prominently on our list, just as on the internet. But our list of 50 are mostly not ad-funded publishers. Instead, it is advertising sellers themselves who dominate. It may be telling that advertising sellers are forging ahead of the publishers they serve: Does this inequity point to a problem with the economics of web advertising? Four of the world’s largest ad agencies, which have been buying heavily into digital, are high-rollers in our 50, while smaller companies in the online ad chain are harder to find, with YP Holdings, Yell Group and SuperMedia clinging to the rear.

6. Where are all the startups?

“You know what’s cool? A billion dollars.” The hottest young startups are all but absent from our list. Spotify doesn’t yet make the grade, Twitter is still M.I.A., Flipboard isn’t yet threatening an entrance. But Zynga, Groupon and Facebook have graduated startup school and are playing with the big boys, overtaking old-line media behemoths like Gannett, Disney and Viacom. Welcome to the club! Don’t be surprised to see more upstarts here in future.

Check out our complete paidContent 50 list.

But what does it take to make money from these fast-growing industries, and which companies are leading the way? Welcome to our second annual paidContent 50 list — our attempt to answer those questions.

The paidContent 50 ranks digital-media companies based not on whether we like their products or are on a first-name basis with their CEOs. We use a very simple and objective metric: the revenue they earn from digital content, or from the adverting around that content. After all, companies ultimately need to earn revenue to survive and thrive — the more of it, the better.

Last year’s paidContent 50  focused on U.S. companies. This year, we’ve gone global, in an effort to better reflect changes in the industry itself.  A growing number of content companies — Netflix, Sina and Spotify, among them — are aggressively pushing into overseas markets ater dominating at home. As that becomes a bigger focus for these companies, you can’t gauge their success without factoring in their track record internationally.

Creating this list wasn’t easy. We wanted digital revenue from the last full year, either calendar or fiscal, depending on the company. To get those numbers, we combed through public filings, read an ungodly number of news stories,  and worked our network of contacts and analysts for data and background. Some media companies break out digital sales for everyone to see, but other companies (and not just startups) make it extremely difficult to discern. With some of those companies, our digital sales numbers are educated estimates based on our research, and in those cases, we list our sources and explain our math. (Read more about our methodology here.)

That Google tops our paidContent 50 list again this year may not come as a shocker. But there are definitely some surprises in this year’s crop of most-successful companies. How much do you know about South African publisher Naspers? Well, it dwarfs many U.S. household media brands when it comes to digital revenue. Twitter is hugely important media company, but it didn’t crack our list (and neither did The New York Times, for that matter). Amazon, on the other hand, is going gangbusters with content sales, as our writeup shows. And as with so many industries, China is becoming a power in media, too.

We’ve tried to be as scientific as possible with this list — the numbers are rooted in raw numbers, not emotions. But no such list is ever perfect. This is a work-in-progress; it’s aimed at starting the conversation about digital success. Please give us your feedback so we can make next year’s list even better.

Additional reporting by Jeff Roberts,
Staci D. Kramer, Laura Owen and Dan Frankel.

More paidContent 50 coverage

pC50: Our 6 big takeaways

pC50: Winners and losers

 PC50: Media innovators

Go to page 2 (of 52) on paidContent .