Naval jelly works OK but if the rust is really bad, try a BBQ grill cleaning pumice block.
You can usually find these at hardware stores pretty cheap - its just what it sounds like, a block o' pumice. Or, you can use your girlfriends' "foot stone" which are also the same thing (but she will be mad!. . .lol).
These pumice blocks are really good at getting rust off of spokes, too - takes it right off in short order. However, it sure won't do chrome any good but if its rusted that bad anyways. . . .
Just be careful where the dust goes though - its wicked sharp stuff and will scratch glasses, your eyeball, etc. so u might want to wear a dust mask and goggles, too.