My amazon list could definitely stand to be shortened. I don't often feel any need to "reward" myself - I guess it depends on what I feel the need to reward. I'm very zen about things, and I tend to feel greatful for my life as it is, but the times I feel I need to be comforted, I think that is the closest answer to what you're asking - and yes, its taken me this long to really think about that...
When I have to endure a LOT of bs at work, or anywhere, I try and balance out those tensed up brainwaves by treating myself to something I've been waiting to buy. I don't like to reward myself with food, so its typically a book, cd, clothing, something like that. Sometimes I reward myself with 20 lashes for even thinking about a reward!
I'm still laughing at the "women workout because..." argument ;)