Well, here's one I just had to enter, and pass along. A chance to win at least 5 stamps sets (and possibly more, depending on participation) is on the "priscillastyles" blog, home of the Midnight Madness Sketch Challenge. Just to note, this one is only open to people with blogs. The contest runs through September 18 (so you have time to enter a sketch challenge, and add to your potential winnings). Good luck!