Over the last six weeks, Google (NSDQ: GOOG) has bought up four startups—and the company’s holiday shopping spree is showing no signs of slowing down. On the heels of Thursday’s news that Google was close to a deal to buy up Yelp for more than $500 million, are reports that Google is looking closely at two more companies. (Update: After this was posted, TechCrunch said the Yelp deal isn’t happening.) A run-down of the latest chatter:

—DocVerse: TechCrunch‘s Michael Arrington says Google is close to purchasing document collaboration startup DocVerse for $25 million. DocVerse lets people collaborate in real-time using Microsoft (NSDQ: MSFT) Office. That doesn’t seem like something that Google would want to help Microsoft out with, considering online collaboration is a major selling point of Google’s own Docs and Wave. So, it would seem that Google is trying to get DocVerse’s talent, which includes Shan Sinha, who drove product strategy for Microsoft’s SharePoint and SQL Server.

—Trulia: Kara Swisher at AllThingsD says that Google is in talks to buy real estate search engine Trulia, which she says is valued at between $150 million and $200 million. Google’s interest comes as the company has expanded its own real estate listings on Google Maps, which presumably could be bolstered by buying Trulia.

So, what else might Google be eyeing? So far, Google’s acquisitions not been focused. The company’s recent purchases have spanned its many businesses, including Teracent for display ads, Gizmo5 for Google Voice, adMob for mobile ads, On2 for online video, reCaptcha for Google Books, and AppJet for Google Wave.

But the interest in both Trulia and Yelp indicates that Google wants to boost its position in specific search verticals. (Indeed, CEO Eric Schmidt suggested as much during the company’s most recent earnings call when he said “in search, there are a number of companies that we’ve looked at—again, small companies that have invented some very interesting way of doing, for example, a kind of vertical search or a kind of analysis of how search should perform”).

In that sense, one gap in Google’s current line-up of search offerings is travel. That hole is especially glaring considering that it has been a priority for Microsoft, which has heavily promoted Bing Travel, which lets users easily find—and book—flights and hotels online.

• Google Expands Real Estate Search On Maps
• Google Reportedly In Talks To Buy Yelp