From the MAKE Flickr Pool:
OverWired designed and built this PC-based jukebox using arcade button switches and a KeyWiz keyboard controller.


More KeyWiz info from RetroBlast:

The KeyWiz Max 1.5, by Groovy Game Gear, is a PS/2 keyboard encoder for MAME controller applications. It’s a compact 32-input encoder unit, with a “Shazaaam!” shift function to double the number of effective inputs.

overWired’s jukebox on Flickr – Link

KeyWiz on Retroblast – Link

Homemade touch-screen jukebox
Homemade touch-screen jukebox – Link

iTunes jukebox physical playlist device
“iTunes” jukebox – a physical playlist device – Link