Google Checkout is offering $10 off a minimum $10 purchase from a bunch of vendors including Buy.com and Mags4Cheap.com until December 31, 2006. I like the deal at Mags4Cheap.com because you can apply it to comic book subscriptions. The cheapest you'll pay for a Marvel subscription is $20 from the Marvel.com website, but with the $10 off from Google Checkout at Mags4Cheap.com, you can get a subscription for $14 or less. Not too shabby.
The catch is you are only supposed to be able to use it if you are new to Google Checkout. This means you have to use a new Google account and a different credit card than what you may have already registered with Google Checkout. Getting another Gmail account is no big deal and most people have more than one credit card, so this shouldn't be much of a problem. I wonder, can you register debit cards with Google Checkout too?