I think it's a terrific idea and I'm disappointed not to see more replies, maybe people just missed this thread... Bitcoin is also considered tax-evader currency, so it would be very good to send a message that the Bitcoin community actually is willing to give money to good causes.
I've been thinking about setting up a Wikipedia fund. The idea is to collect bitcoins for Wikipedia in a public manner, the idea being that Wikipedia will get that money as soon as they start accepting bitcoins. What I want to say is "Hey Jimmy Wales, here's how much money you're missing out on for not accepting Bitcoin".
I probably don't have time (or rep) to follow through with this idea so please feel free to use it, should be good for other good causes as well.