SwipeGood is a neat idea: Each time you use your debit card, automatically give change that would round up to the next dollar amount to your favorite non-profit or charity.
You can put a cap on the amount you donate monthly.
It’s a start-up, so there are not a lot of participating charities yet. (I chose Hub City because I saw the idea on their Facebook page.)
If you are interested, use this link and get $10 to give to your cause of choice.