Apple on their store sell the iPod In-Ear. For 39 Euros, it will replace the original one. Yet if you're ready to try a more expensive one, why not try the Etymotic Er-6i Isolator.
Thoses headphones we tried are way better. Their dynamic is quite superior, you'll even encode some sogs in better quality after using them. Its main advantage is to provide a real isolation from the outside. To give you an idea, wearing those and listening to your songs at a moderate level, you won't hear the bell in the parisian subway.
Be careful though as those advantages may become drawbacks. Do not use in a car ot on a bike, it may be dangerous. The provided sound output will be higher than that of Apple's headphones, you'll have to get used to it.
You'll also have to get used to plugging it deep in your ear conducts, which may feel a bit weired.
Yet if you're ready to invest over 140 Euros, you'll get the best out of your iPod using this.
