Sharpies are wonderful little things- you'll find a million uses for them once you've bought a pack. They write on greasy/slick surfaces just fine, will never, ever rub off, and are a dime a dozen at that.
For the uninitiated, a Sharpie is a permanent marker with a unique alcohol-based ink that will never, ever come out. My understanding of it is that the pigment and alcohol seep into the paper, but when the alcohol evaporates the pigment stays locked into the paper. Same thing with slick/greasy surfaces, just it doesn't soak in. In any case, they're useful for absolutely everything- the ink is incredibly dark (assuming we're talking about black, which is the standard shade everyone uses), and assuming you don't leave the cap off they've got pretty good lifespans for markers. The only thing you can't use them for is highlighting, because even some of the coloured versions will completely obscure the text... the ink is that strong. That said, though, it has its' downsides- the ink tends to soak into 5 pages all at once, screwing up anything you've got underneath. Because its' alcohol-based, they've got a modest lifespan once you open the package- usually about 6 months or so, and that's assuming it's unused and with the cap on. And if you ever get some on your clothes, just throw the item out- unless you have a laundry machine within 5 feet of you, it's stained permanently.
The Sharpie's a great marker for anything and everything under the sun- street-taggers put up graffitti with them, and cops write reports with 'em once they catch the taggers. They're the best markers under 10 bucks, bar none, so how could you go wrong?