Goodsearch is a search engine powered by Yahoo that donates around a penny to a charity of your choice every time you do a search. The donations are raised from 50% of the advertising revenue. Apparently the Dance marathon chapter raised $900 for a children's hospital.
Goodshop was recently launched and it donates 37% of the sale of any goods purchased.
The results are decent too. Give it a go, especially if you run a charity.