You can use Brasso, it is perfect for removing scratches from CD's, plastic lenses, old record player lids. Its a mild polishing abrasive designed for polishing brass, but is superb on plastic, or you could try t-cut, but in both cases be gentle, do little then polish.
I don't have an iPod myself, but I know you can get replacement housings from ebay if the scratches are that bad: http://search.ebay.com/ipod- housing_W0QQcatrefZC6QQcoactionZcompareQQcoentrypageZsearchQQcopagenumZ1QQfnuZ1QQfposZQ5AIPQ2fPostalQQfromZR10QQfsooZ1QQfsopZ1QQftrtZ1QQftrvZ1QQsacatZQ2d1QQsadisZ200QQsargnZQ2d1QQsaslcZ2QQsbrftogZ1QQsofocusZbs
Well, as far as "iCondoms" go, the iSkin is one of my personal favorites. It keeps the click wheel protected and usable, even!
Crap sorry I just noticed I posted the wrong link and was too late to edit it. http://search.ebay.com/ipod-housing_W0QQfkrZ1QQfromZR8
Just search "iPod housing" on ebay and you should find what you were looking for.
I didn't make it!
Oops, I meant to post www.shieldzone.com . It has a product specifically called applesauce which works great. I also recommend buying one of those shields as they are invisible and protect your ipod against scratches.