Wikipedia is something of a modern day miracle. It's a free, perpetually up-to-date, nigh-all-inclusive, readily accessible encyclopedia that has long proven to be about as accurate as more traditional alternatives. The easy thing to forget, however, is that this is only because an army of Wikipedians is dutifully editing, re-editing, and re-re-editing the site's myriad pages. Unfortunately, there seems to be a downward trend; the number of new Wikipedia Admins has dropped off, and if the pattern continues, the site could face a very serious shortage.
You might not be allowed to use it for school papers, but Wikipedia is effectively the go-to source for information in most of the non-graded sectors of the world. The thing we tend to forget, or at least not think about very often, is that Wikipedia isn't written in stone. In fact, it changes faster than you can imagine. Wikistats, a new site that tracks the "trending pages" on Wikipedia, can give you good idea of what's changing at any given time, and by how much. The results might not be what you'd think.