removing rust?

Rust Ring Emergency!!

Anyone know a good way to remove rust?!?

...Well it's not as bad as getting arrested or breaking your fibia, but it could cost me a BUNCH. (You don't want to know how much money in security deposit I have on my apartment!!) So I qualify it as an emergency.

I don't have anything abrasive enough to get it off. Ideally I'd whip out the ol' 4 inch rotary grinder. (If I had one.) But... if I go too abrasive it'll mar the surface too bad. And it seems like most of the sink has a coating--probably something made of plastic. It'd be nice if I could scrub only where there's rust.

Readers in Japan: is there any product I should know about? All the American products I know are not available here.

..This is the second rust spot to stain something permanent in my apartment. The first was my plastic sink in the shower, from the bottom of a shaving cream can. Yes, Plastic. Plastic got stained by rust. It just grew down into it somehow. The same thing happened here.. standing water does nothing to the sink when it's just water, but when in contact with a Cambell's Chicken Noodle for a day when a guy is sick... Actually, I'm sort of lucky it was just a ring, because those cans have multiple rings now, and there's a sticker for Japan import on the bottom. Anyway.

I'll go buy some fine steel wool and see how that goes. Maybe I can show the above photo to the old man at the nearby hardware store... And as a last desperate resort I might try ammonia, although I happen to know it doesn't have the redox potential to reverse iron oxide.. *gack*