If you're a BoA customer, I'd recommend that you sign up for their Keep the change program. It is really cool and it works great. I started like a week ago and I have about $60 bucks already added to my savings account. The way the program works is that all the purchases you make get rounded up to the next dollar.
The difference between your actual purchase and the next dollar automatically gets transfered from your checking into your savings account, and then to top that, BoA will match %100 of that for 3 months up to $250.00. After this honey moon period, they will match 5%! Now THAT is free money.
You'd be surprised how quick it adds up. Since I already use my atm/check card pretty much exclusively I didn't have to change any habits or anything to start using it. If you have BoA then give this a try, enrollment is free.
Updated 2021-11-26, formatting issues.