Coupons.com is now offering coupons that you can link to your credit card. It seems to function the same way as the discount programs used by banks for use of their debit and credit cards. The nice thing about these is that they can be stacked with other offers, and since this isn’t being offered by any particular bank you can use whatever credit card you want.
The best deal they have at the moment is $20 off $200 at Travelocity (UPDATE: Thanks to the Freequent Flyer for pointing out the Travelocity deal doesn’t work for flight-only purchases). Here’s the entirety of what they’re offering right now: