Invulnerability is one of the coolest things you can do in terms of having powers. You can hurl yourself off cliffs and flips cars, stuff like that, without being hurt. You can get into pretty much any kind of creative situation. How about manipulating the earth, raising continents, or controlling water/fire?

There's actually some pretty cool ideas in the 1000 Things to Do in an LD thread; if you continue reading, you're bound to find something!