1. Built-in speakers. You can take off your earbuds and switch these speakers on. Handy for times when you want tunes, but cannot wear earbuds (like talking with your buds).
2. A built-in jack. This way you can plug your MP3 player directly into an AUX port, without having to switch to another cord entirely. This would flip out of one of the earbuds like a switchblade.
3. Visualizer. Okay this one is entirely cosmetic, but I always liked the idea of a visualizer on the earbuds or the MP3 player itself. Sure it’s a bit Lady Gaga, but it looks cool.
4. A spare jack port for sharing the audio feed. Sure it seldom ever happens, but this would be nice feature that would allow a friend to listen in. Handy for when you want to a share a film on a long flight. You could buy one of those splitters, but they are never around when you need one.