In addition to the list from the Bitcoin wiki is the list of charities in which donations through Witcoin can be made.
 - http://witcoin.com/charities

Any charity can register to be included.  Those who post, vote or reply on witcoin can configure their Witcoin user account such that a certain percent of the proceeds they earn after post, reply or voting can be donated to one or more charities of their choosing.