Obviously it's the Triforce from The Legend of Zelda for me!
Other than that... I know I'm not allowed, but I like this very much:
That's the only symbol I'd like to have a tattoo of.
Random game thought :
Why is Bionic Commando Rearmed 2 getting so much hate? We finally get a real game and they're not even satisfied... I'm starting to hate the gaming community so f****** much...