I have the full body Invisible Shield for my 60g Vision:M and it's great.
Basically, it fully covers the player in a clear plastic shield, so stops any scratches at all, you can even rub scissors over the screen and nothing happens, I've done it.
Here's some info from their website:
Made from a unique material originally created for the military to protect the leading edges of helicopter blades, the invisibleSHIELD™ offers protection that other screen protectors just can't match. With over 800 copyrighted, precision-cut designs for a variety of gadgets, including MP3 players, PDA's, and cell phones, the invisibleSHIELD™ is the industry leader in screen protection.
If you aren't completely satisfied with the coverage of the invisibleSHIELD™, you can return it within 30 days for a full refund. And if your devices ever becomes scratched or damaged, you can replace it for free. So what do you have to lose other than those unsightly scratches?