checkout.google.com
if you have a gmail account, it's even easier to set up.
1. register
2. attach a credit card to the account and done.


go to a supporting site: (buy.com, etc)
shop normally and hit the price breaks ($10 off of $30, $20 off of $50)
when you're ready to checkout, you're given 2 routes
1. normal
2. google

use Google and you're sent to the Google Checkout. It's only 2 steps long.