I give myself rewards! I just reached my first 20lb mark today so I spent $20 on costume jewelry from Forever 21 (they have AWESOME jewelry for waaaaay cheap, check out their online store - it's much more organized!!!
http://forever21.com). If I'm buying myself something, I think a reasonable award is $1.00 for every pound lost.
Other rewards I have planned:
-Clothes when I get closer to my long-term goal weight
-SPA DAY!!!!! This one can be an at-home spa day, a trip to the salon for a mani/pedi, OR a full-out professional spa day - which I've never had before ever so I think that's what I'll be rewarding myself with when I get to the halfway point :3