Widget analytics and distribution firm Clearspring has made a small tools acquisition: it has bought AddThis, the bookmarking and content sharing tool used on many blogs and publishing sites. AddThis was launched in Sept 2006, and based in Princeton, NJ…it aggregates many social media services including all majors such as Facebook, MySpace, Digg, Twitter and others. Earlier this year Clearspring raised a big $18 million third round led by New Enterprise Associates…it has raised a total of about $35 million till date, and has Steve Case, Ted Leonsis, and Mark Jung as investors. Kara spoke to Leonsis, chairman of the board at Clearspring said that AddThis has negligible revenue and ClearSpring has about $10 million in annual sales. Neither is currently profitable.

More details in the release.

• Widgeteer Clearspring Gets Its Big $18 Million Third Round
• 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