A Slate article notes the paralells between Wikipedia and The Hitchhiker's Guide to the Galaxy:
It's too bad Douglas Adams wasn't able to see his vision brought to life. I don't mean the so-so movie version of The Hitchhiker's Guide to the Galaxy. I'm talking about Wikipedia, the Web's own don't-panic guide to everything.
The parallels between The Hitchhiker's Guide (as found in Adams' original BBC radio series and novels) and Wikipedia are so striking, it's a wonder that the author's rabid fans don't think he invented time travel. Since its editor was perennially out to lunch, the Guide was amended "by any passing stranger who happened to wander into the empty offices on an afternoon and saw something worth doing." This anonymous group effort ends up outselling Encyclopedia Galactica even though "it has many omissions and contains much that is apocryphal, or at least wildly inaccurate."
The article goes on to offer some criticism on the Wiki form of things, most of which I think is fair. I'm not a huge user of Wikipedia, but I do think it's nice to have that ever-expanding, if somewhat unreliable knowledge base.