I don't have an iPod and I haven't really used them, but I did want to note that if they're anything like Apple's In-Ear Headphones, they probably blow. Those headphones are slightly different in that they have a plastic covering (that come in 3 sizes for comfort) that channels the sound into your ear rather than simply being padded over. They're comfortable to wear, until you start playing music, at which point the complete lack of bass and sound balance gives you a blistering headache.
Anandtech did a comparison of in-ear headphones a way back, and it seems that Sony brand headphones generally have more bass and powerful drivers to give you a more well-rounded sound. I haven't done too much digging into headphones, but I'd start there if you're looking to buy a new pair of headphones.