Just a personal anecdote. I'm currently preparing a trivia quiz in a very similar format to one I did 2 years ago. Then, I don't recall using Wikipedia much - I just got on the web and searched for the answers to questions I came up with. This time, I'm using it almost exclusively - it just seems to have become that much more useful.

It's brilliant on: - Storylines of popular soap operas - Train stations - Winners of major sporting events - Participants on reality TV shows

It's somewhat less good on: - Ranking Australian cities by size (the formats of the articles are too inconsistent) - Finding people who had died of certain unpleasant diseases. (There's a rough list of survivors/victims of testicular cancer, but couldn't find the same for anal cancer. Don't ask...)

It's (understandably) no help at all on: - Lyrics of popular songs

I guess we malign Wikipedia a lot for its coverage of popular culture, but on the rare occasions you actually want that, it's pretty damn useful :) And it's just astonishing how the whole method for preparing something like a quiz has just totally changed due to this one fantastic resource.

Steve