I'll be honest with you, IMO screen protectors are useless. First you gotta deal with the price, then applying and making sure you dont have bubbles, then you gotta deal with maintaining them. Sometimes the corners un-stick, sometimes dust gets stuck on the boarders...ah it's a mess for no reason. Hold on for awhile and watch where you put your iPT is my only suggestion. Eventually you'll see some good products to protect your iPT like they've done for other iPods.
Just be careful
Edit: And if you really want one, their is one in particular that attracts a lot of buyers. I can't remember the name, if you do a quick search you're bound to find it, i'm sure.
Be very careful! I put an IS on the back of mine but didn't put the front part on because I thought the screen was quite resilient. I always keep it in a sock, too.
Anyhow I went to use it today and... yup the screen has a scratch! Have no idea where it came from. Must be my pesky kids
Actually, it's not bad at all - it's right in the left bottom corner on the black screen surround so it doesn't get in the way - but it proved to me that the glass isn't as resistant to scratches as I first thought.
So tonight I'm putting on the front IS before I get any more!
You know come to think of it...because the iPT front is flush, i don't think it'll be as bad as i think it'll be (gooder english ). I've had experience with Palms, cellphones and a DS lite (worst purchase i've made to date, hahaha) and it's been nothing but bad news with these protectors. Anyways...each to their own