Oooh, coupons!

RetailMeNot.com, a site by the guys who did BugMeNot (the thing that let you skip registrations for sites).

Apparently this one lists coupon codes, as well as success rates for codes. Pretty spiffy.

For example: http://www.retailmenot.com/view/victoriassecret.com

They've got amazon, buy.com, and a ton of other places.