Stamp It! Cards. If you've not picked up your copy yet, I HIGHLY recommend it (and not just because they're a certain someone's card on page 16). It is jammed packed with incredible ideas organized into all the major card categories from All Occasion to Wedding. The magazine retails for $5.99, and you can get 20% off by entering the code "STAMPIT20" here.
And here's my first published card: