I've still got all the parts for a MAME machine sitting in my work room.  I started building it about 2 months ago, but I cut some panels wrong, and gave up (temporarily) in disgust.  It's a great project, I just don't have the attention span for it.
My project is actually a portable MAME machine.  It's a 24""x10"x6" acrylic box with 2 player, 6 button controls and a trackball on the top.  Inside is a MicroATX motherboard & power supply, a 7 gig HD with a complete MAME 0.69 romset, and a VGA-TV converter.  On the outside will be standard RCA audio and video jacks.  You can take it wherever you want, plug it into a TV, and you're ready to go.