If you're running a successful startup and looking for some kind of charity outlet for some of those profits, I highly recommend Kiva loans. Find some entrepreneurs trying to start tough businesses in tough environments, like a tailor in Liberia or a corner shop in Congo, and loan them solid chunks of money (e.g. $500 at a time).
If they repay the loan (which the ones I loaned to have so far), then:
1) you've helped start a business in a deprived part of the world, possibly changed someone's life
2) you've got the money back to help another business
And in either case:
3) you've done something very tangible to help another entrepreneur who is dealing with business risks you are lucky to never need to consider in your entire entrepreneurial career.
