The iSpin is a mixer that uses two docked iPods as inputs, and provides a range of effects like reverb, flange, hi/low pass filter and scratching sounds. While this would be fine for some DJs, it won't suit everyone because you can't beat-match with it.
It's probably more suited to a house party than a club, but at $140 it's a fun piece of kit. It's available in isilver on white or red on black, to match your iPods. [iLounge]