A couple of months ago I got a 20GB iPod, which, for those of you who have been living in a cave the past couple of years, is the most popular portable digital music player in the market. Apple owns the market with something like 75% market share for a number of reasons. But that's a marketing and technology discussion that should probably be reserved for a separate entry. I have a much more practical piece of advice for iPod owners - get some protection if you care about how your iPod looks. Along with many other users I discovered that the iPod is fairly prone to scratches - especially the stainless back and the LCD screen.
There are different schools of thought here. You could buy a case made of neoprene, nylon or cloth which fully covers the device but you have to make sure whether there are holes cut for the recharging ports or headphones. Full body cases often add bulk as well. The alternative is to use thin plastic films that adhere to the iPod and protect strategic areas such as the LCD screen and metal back. An example is TrendyGeek's PodShield which I ended up using and have been very happy with. Another variation is full body plastic film such as InvisibleShield (link to review).
Apparently the new iPod nano has been getting complaints about its sensitivity to scratches and LCD screen cracking. Whether it's a design/manufacturing flaw or not, it's a good idea to get some kind of protection. I'd recommend the plastic film approach if you're concerned about adding bulk or weight to your iPod.
On a related note, I wouldn't be surprised if there are some musically minded gents who have had jackets made with custom-made interior pockets for their iPods.