LOL, I already have MvC2 and Splosion Man. I got like every random arcade game that looked somewhat interesting.
I ended up getting Ninja Gaiden Black, which I debated a lot about, because I could get the actual physical game pretty cheap. But, no, I talked myself into it. And... it refuses to play. I was eager to totally blame MS but after a little research, it looks like its because I have an unofficial modded harddrive. Don't have any problem with other games, but since the game is 6 gigs somehow something doesn't work. Boo.
Anyway, I'm at work and don't have the link to the dude's page here, but I'll try to post it later when I'm home.
The catch is he doesn't really just sell you a points card, he sells you an account loaded with points, so, you have to keep the random weirdly named profile on your Xbox in order to play the games you download. But... hey, its worth it, for the money, I don't really care if there are a few random accounts sitting there.