Just in case you haven't tried it, you can really clean up the back of iPods with scuffs on their chrome backs. Brasso® metal polish is around $3 a can, much cheaper than those specialized iPod cleaners. Here's a before/after of a fairly scuffed up iPod. I only did a minimum of rubbing and buffing. It won't eliminate them completely - you're still going to have a duller than usual back. But it does brighten the appearance. It also works on the front plastic, without marring it.