Seeking to expand its Internet presence and hasten its transformation from an ISP to a Web 2.0 company, AOL said today it has acquired blog content company Sphere Source.

Sphere, which began life in 2005 as a search engine for blogs, provides a Web site widget that calls up relevant content from a variety of sources across the Internet, primarily blogs. The Sphere link is found on over 50,000 sites, including those of media organizations CNN, Reuters, Newsweek, and CBS.

For AOL, the acquisition is part of a plan to break out of its original access-provider niche and add a range of content and services from across the Internet. Last month AOL purchased Bebo, a U.K. social networking site, for $850 million. It has also been linked to a possible merger with Yahoo, which is attempting to fend off a takeover bid from Microsoft.

"AOL is doing what great, sustainable business do every so often -- they're reinventing themselves," wrote Sphere CEO Tony Conrad on the company's blog today. "They've seen steady growth as a result of the extensive programming and product upgrades they've made in the past year."

Founded in 2005 in San Francisco, Sphere faced a market crowded with startups like Technorati as well as major players like Google, which launched its own blog search feature in 2004. Sphere quickly shifted gears, adapting its business model to equip big media providers with a simple technology for "contextual search" -- i.e., displaying relevant links and content based on the subject matter of the page being viewed.

"We founded Sphere with a mission to make contextually relevant connections between all forms of content (mainstream media articles, archived articles, videos, blogs, photos, ads) that enable the reader to go deep on topics of interest," wrote Conrad.

The terms of the deal were not disclosed, though several tech blogs including Techcrunch estimated the purchase price as $25 million.