Bank of America has a great new idea out.
Every time you buy something with a Bank of America Visa® debit card, we’ll round up your purchase to the nearest dollar amount and transfer the difference from your checking to your savings account free of charge.
In other words, if your coffee costs $3.57, you’ll pay $4.00 and they’ll put the $0.43 in your savings account for you. It’s not much, but it’s a good start and it adds up.
Why didn’t I think of this?
Link via Signals vs. Noise (see their discussion of Keep the Change)
Update: Dale points out why I am wrong in the comments.