>You probably need open source/Wikipedia style alternatives to prevent abuse.

Wikipedia is a bad example, as there is plenty of abuse there [1].

[1] http://www.smoblogger.com/wikipedia-sucks/ http://homepage.univie.ac.at/horst.prillinger/blog/archives/... http://answers.yahoo.com/question/index?qid=20100506025259AA...

Many more, but it's hard to find them since putting "wikipedia" in your search now causes google to look up those words on wikipedia itself first...