No matter how you look at it, headphones are needed. Some people own a pair, while others have a dozen. This doesn't even start to consider the ones that are currently broken. So what kind of headphones should you look for, a pair that does everything, or a few pairs that will take care of business?
Common logic dictates that you should have a pair that does everything, but we've found that it's best to have a couple of headphones around for different tasks. First of all, you need a pair for your iPod/mp3 player. A decent pair from Shure or other manufacturers will make a lot of difference in the audio quality. Noise cancellation is cool, but expensive. If you budget between $100-200, you'll have lots of choices. The most important thing is that these earphones need to stay in your year while you're running around town.
When you're at home, you need a decent pair of headphones to listen to music, to movies, etc. This is really nice to have especially when you can't use the speakers. A good pair of headphones can stay on your ears for hours. I've always had good experiences with Sennheiser headphones for this part. It's important to get headphones that have a replaceable cord, because the jack can easily snap off when the computer speaker falls to the floor. I've broken 3 pairs of headphones this way. At around $200, you can get a great pair for this task.
Lastly, a decent Skype headset is needed if you use Skype a lot, or some other form of voice IP protocol that necessitates a microphone. The USB telephone handsets that are available are interesting and make Skype seem more like a normal phone, but when you videochat, a headset is cool. The benefit is that your conversation is more private. This is important if you're in public or at the office.