Stack the Mac Mini with an Apple PVR?
The Mac Media Center forums had this to say about the power connector of the Mac Mini potentially having more "lines" than needed:
It has been speculated that this port could be used to stack something ontop of - or under - the mini. For instance, have you heard of the rumored "asteroid" audio input/output device? its supposed to be about the shape of the mini and fit snugly ontop of it. If you could daisy-chain devices to the mini's "power" port like firewire, it could be extremely useful (and stylish too).
This rumour stuff is fun!