http://bitcoin100.org/
That project hasn't really exploded yet but it's just a matter of time. There is currently 266 BTC just waiting for the first charity to add Bitcoin donation option through the Bitcoin 100 project.
Donations involve a lot of micro transactions which is the main reason why it's only a matter of time before more and more charities start endorsing Bitcoin. It's just so much cheaper than the alternatives and convenient as well.
+1 good cause
Isn't there somebody providing hosting (paid for in BTC) floating around on this forum too?