I suppose TOMS we're the first with their 'one for one with every pair you purchase TOMS will give a new pair to a child in need' campaign in 2006. Certainly its working worldwide!
For every new Facebook fan who joins them from now until the 10th May they will buy one book for one child in India for a day with their partner Pratham:
1 new fan = 1 book per child
Now, I think this idea really works! And Armed Angels have a pretty cool selection of tees too!