Both the Ultimate Ears Super.fi 3 and Shure SE115 are good earphones for the iPod. The UE Super.fi 3 is relatively light on bass response, with the SE115 being quite heavy on bass.
Others good iPod earphones worth considering:
Sennheiser CX550 - In-ear earphone with sound isolating design. Good sound quality. Robust build quality. Excellent bass response and clarity of trebles, with mids a little recessed. Ergonomic design ensures comfortable fit. Comes with Sennheiser 2 year warranty.
Shure SE110 - In-ear sound isolating earphones. Well balanced sound, with excellent accuracy of mids/highs. Comfortable fit and sound isolation, especially with supplied foam eartips. Less bass response than SE115. Solid construction with 2 year Shure warranty.