These headphones are pretty neat. The cables have EL wire sleeved up with them that beats with the music. It's being hocked as an iPod accessory, because we all know that the iPod is the Only Music Player Of Any Kind In The Entire Universe, EVER. But it uses a standard 3.5mm stereo plug, so you could use it with anything.
I don't know why this would be at all useful, it's just a nifty idea. You could make such a thing pretty easily yourself too, but they're only $30, so unless you already have a lot of the parts lying around it's almost not worth bothering.
Edit: Also, I would note, that if I were to make such a thing myself I would want to either a) Power it through the headphone line if at all possible (possibly not enough power, though I've powered some pretty big speakers through my mp3 player before, so...), or b) Power it off a smallish rechargeable lithium-ion battery, because I would not be enthusiastic about carrying around an extra two AAA batteries to make it work. Not a *huge* deal, just not enthusiastic.