I try not to buy myself anything when I'm Christmas shopping. Usually, money is pretty tight around Christmas, and my birthday is the day after Christmas, so I get a lot of presents at Christmas time.
I do have a blast shopping after Christmas, though! I always get a few gift certificates, and a few items I need to return, so I have so much fun buying things I liked while Christmas shopping at about 1/2 the price! Last year, I had to return 3 Gap sweaters that were too big, and I ended up getting 3 sweaters, a pair of pants, and a belt with the credit I got.