Hmm. I'd wish for 10,000 wishes. If that couldn't be done, then I'd wish for a gigantic sum of money, like, several hundred billion dollars. Or for a permanent end to war and hunger throughout the world. Or maybe to be the greatest guitarist or drummer of all time. That'd be sick. Or for the godliest MW2 skills known to man. Like, freaking amazing.
A million wishes, I suppose. And then I'd think out every single wish from then on very, very carefully. I don't want to be responsible for messing up the world...
One wish? Omniscience. I could see everything, I would know every life form that exists and did exist (which would fascinate me, thats why I mention it), I would know a solution for every problem.. and many smaller practical stuff, like knowing if and where I or other people had cancers, I would manage my studies with a perfect, and so on.. ^^