In yet another somewhat misleadingly titled article, experts are warning that many listen to portable music players at volumes that are way to high. According to the article, this is, in large part, due to the earbud style of headset. Because it lets in a big percentage of outside noise, users tend to turn up the music more. 110 to 120 dB (Decibels) on average.
I am an avid music listener, though it is usually on my computer that I carry out this activity. I have a laptop, so I find that more portable devices tend to work better for me. One time (I think 2000 or 2001) I went to CES (Consumer Electronics Show), and saw the Shure booth. Yes, they have some of the coolest wireless systems known to sound technicians, but I saw the earbuds associated with the in-ear monitors for musicians and tried them. On putting them in my ears I was impressed with how quiet it became inside my head.
I could hear clearly the music that was playing, and the buds were small enough to be practically invisible. This link is to the brand I have. There are other good brands, though. Yes, you will spend some money, depending on what you want. You could spend $100 bucks now, and have your hearing later, or not spend the money, and not be able to listen to any music later in life.
A side advantage to this style, is that in-ears tend to seem louder (because they are closer to your eardrum, and because they create a closed space in your ear), so the end result is longer battery life. I have found that, compared to my studio quality Sony headphones (which list at about $100), my $70 Shure headphones take 50% of the output volume from any given device (and they are more accurate with frequency response).
If you got an iPod (or other personal music player) for Christmas, look into this style of headphones. They are quiet, sound better than most any other type of headphone, and are well worth the money spent.
If you are considering a noise cancellation headset, try these first. I have used them many times on planes with a very pleasing result.
For the most pleasing result, it is possible to get ear-moulds (just like for hearing aids). This is what most musicians are doing, and it gives the most comfortable fit, along with the best isolation possible.