Why?: Good ideas!
The other option is to grab an external drive case and put the USB hub, big-ass audio amp, external hard drive, or other +12V-consuming device *into* the drive case.
Pics for days 2 and 5 are relevant to this thread.
A neat gadget I saw not too long ago was an audio amp in a 5.25" form factor. Back end is a cable with a bunch of connectors for two audio channels and a subwoofer, front end had a headphone jack, programmable memory settings for what appeared to be a graphic equalizer, and/or a very basic (5 LEDs, one for each frequency!) frequency spectrum display. Power was from a standard 4-pin PC plug - +5 and +12. Almost makes me wish I had a third bay in my hacked IDE box!