Sorry about that. Rant over.
I have a real one that you actually see in some movies/comics/whatever. The ability to make yourself "insubstantial" so bullets, fists, explosions etc. go straight through you.
Think about this one, there are two ways it could work:
1) Only matter goes through you, you're still affected by forces such as gravity etc.
2) Nothing affects you, the laws of the universe dont apply.
In either case.
1) You fall straight through the earth, pulled by gravity to the core where you remain eternally.
2) You are released from the loving caress of the earths gravitational field, to float upwards as the planets orbit pulls it away from you, leaving you floating in empty space, where you remain eternally.
Fun either way, huh?
EDIT- I thought about this, and actually in the first scenario you wouldnt stop at the core, your inertia would mean you would get to exactly the same distance from the core as you started in the opposite direction, i.e. the exact opposite side of the world, then start going back again, ad infinitum.