From MetaFilter, great ways to have fun with Wikipeida:

First, find a useful Wikipedia article that normal people might read. For example, the article called “Knight.” Then, find a somehow similar article that is longer, but at the same time, useless to a very large fraction of the population. In this case, we’ll go with “Jedi Knight.” Open both of the links and compare the lengths of the two articles. Compare not only that, but how well concepts are explored, and the greater professionalism with which the longer article was likely created.