Another hefty late stager: Widget analytics and distribution firm Clearspring has raised an $18 million third round led by New Enterprise Associates. Past backers including Novak Biddle Venture Partners also participated. The McLean, VA-based company has now raised $35 million, including two previous institutional rounds and a seed round. Among its previous investors: Steve Case and Ted Leonsis, and Mark Jung, the former COO of Fox Interactive Media (NYSE: NWS). Anything widget-related is pretty hot right now, and Clearspring is looking to capitalize via in-widget ads and the distribution of widgets-as-ads.

I asked CEO Hooman Radfar about what to make of proliferation of companies in the widget sector: “Where we stand is that we generally think there’s a healthy ecosystem that’s going to continue to grow.” But he added: “You literally can’t have as many companies that there are.” We also discussed whether there was tension brewing between the widget or app-based ad networks on social networking sites, like Facebook, and the banner-based ad operations of the sites themselves. Radfar thought it possible that the networks could impose some sort of ad revenue tax on developers. But ultimately, he suspects they’ll find models with more depth and potential than a crude tax (all the best luck on that).

• Widget Firm Clearspring Receives Additional $10 Million In Funding
• Widget Tools Firm Clearspring Gets $5 Million From Case, Leonsis and Jung
• Content Widgets Syndication Firm Clearspring Gets $2 Million Funding