It might just be because most of my friends have an xbox, but I'm basically the other way around: I can get all the titles I'd want to play on an xbox so why bother with a ps3? Basically, the only thing that *would* have talked me into a ps3 over an xbox (ff13) ended up being cross platform, so. I guess the main exception is the Yakuza series, but since my friend has a ps3, I'll just be playing it with him. The games I am interested in playing: Assassin's Creed, Alice, Prince of Persia, etc are all cross platform.

There is a list on wikipedia that you can sort based on whether the game is exclusive to ps3, which might be helpful for you. Here.