Nowhere on the Internet does this free lunch logic hold more true than at Wikipedia, the free encyclopedia anyone can edit. Sure, it's monetarily free, but it costs you heaps in credibility and accuracy, as well as the time spent combing over information for instances of "jason is a faggit" and other assorted such delights hidden mid-paragraph here and there.
Something Awful has a flat out hilarious (if somewhat long in the introduction) article on the nerd bias of wikipedia. The point isn’t to say that one article or another on Wikipedia has factual inaccuracies, but rather to show how much more attention certain topics get than others.
A columnist for the Syracuse Post-Standard apparently recommended Wikipedia as a good independent source for information. However, a librarian wrote him to complain about Wikipedia, and now another columnist has decided to spend an entire column bashing Wikipedia as a source because (gasp!) "anyone can change the content."
There's been plenty of debate over the past couple of years about the merits of Wikipedia, generally focusing on how "trustworthy" the site is because of its anonymous contributors and lack of professional editorial review.
T. Hampel, T. Pitner, and J. Schulte. ICEIS 2008 - 10th International Conference on Enterprise Information Systems, page 107-112. Barcelona, Spain, (June 2008)