Like body tattoos dating back to Eurasian practices around the 5th millennium BC, people will always have the human urge to express themselves in such a mass consumer culture. Luckily, since gadgets these days can almost pass as another part of oneself, 3rd party sticker companies have continued capitalize on this form of expression for years now. On the other hand, some of us continue to feel that putting a little graphic on an already well-designed product is a slap in the face to the industrial designers.
You could also custom your iPod or iPhone - the possibilities are endless when it comes to easy-peel vinyl stickers.
For the curious, the skins featured in this article are all done by European vinyl skins makers Skinizi. Their skins are reasonably priced at about $30 bucks a piece. They're cut and shipped from Europe, so expect about week's wait when ordering.

Nomade Express Slee...
i used to always have cases for my phones, then had invisible shield for my ipods, etc. now i keep my iphone, MBP, and everything else just the way it was made. if it gets scratched it sucks, but who really cares.
i think skinning has a place in the heart of the owner, but not in the spectator. kinda like tattoos.
i never really understood it. i had bought a vaja case with a custom inscription on it for my old sony ericsson w800i. it added about a half an inch total girth to the phone - impossible to have in my pocket. and my old boss used to have an NRA sticker on his inspiron - it looked like he was trying to hide the logo much like you would see on television.
most of my electronics are apple, and i love the design of their items so i leave them as they are!
I have a skin for my old iPod but it's mostly to keep it from scratching. Everything else is as the manufacturer intended it.... my laptop is a Dell, and I chose the pattern on the lid specifically because I love it.
And I don't even want to put any sort of protective case on my Blackberry because it's just so darn pretty (ok, I know I should, but it is so pretty).
I have a vinyl sticker on the back of my macbook (got it from here: http://www.etsy.com/shop.php?user_id=5283842). I'll admit, I got it because I like... but it's also a nice way to ensure that when you're working with 20 other people who have the same macbook (which happens for me more often than not) that someone doesn't accidentally walk off with yours instead of their own.
it depends on how it's done and in moderation to personalize something. most of the time things are best with no logos.
most skins have ugly or uninteresting mismatching design. on the other hand and on occasion i see a great illustration that would make a great skin. for me it has to be aesthetically pleasing, practical, and lend a level of uniqueness.