Today, Slate's explainer tells us that it's illegal to buy votes, even if it's with underwear (a la Michael Moore) [slate].
I hope that doen't invalidate the VOTEorNOT raffle. I could use the cash.
My guess is that it doesn't since you aren't actually required to register or vote to be entered in the drawing. As far as I can tell, the site's purpose seems to be aimed at viral marketing of registration information, since checking-up on voting would be really complicated, and probably illegal.