So over about 6 months last year, I built this monstrosity:



Here's a slightly better shot of the control panel:



From the side:



The cab is built around a 27" CRT using SVideo from an old p4 that I had lying around.  It can run just about anything pre 96, but I've seen it choke pretty hard on anything newer (e.g. Naomi stuff).  It's easy enough to swap that out later though.  As for the other stuff, I've got 3 8way sticks and 28 of the buttons wired through a 4 player ipac.  The p1 stick is an UltraStik with the longer handle and stiff spring, so it's not as loose as it is when they come stock.  I decided to forego the trackball and spinner to save some money and space on the panel for now.  As for the layout, most of the 4p panels I've seen angle the outside players, and I thought about doing that, but this way I have 2 sets of inline sticks for smash TV, Total Carnage, Karate Champ etc.  

Everything runs through a mamewah front end, which works pretty well once you get it tweaked right.  It's great at being able to send pre/post emu command lines though, so I can reprogram the ultrastik based on the input mode for the game.  

As for what's still to do:
-Artwork: what's on the "bezel" and "marquee" (both just cardboard now) is temp placeholder stuff.  I need a decent bezel on there to close it in.  The control panel looks OK, but I'm not that happy with the seams.  The copy I got printed on a single page didn't line up with the holes right (waste of 30 bucks at Staples), so I just did these on 11x17 cardstock on a colour laser.  
-Visual Pinball/VPinMame: Still doesn't work well with Mamewah.  This should just need an afternoon of tweaking software.
-PC Games: Again, a software tweak.  I got the crazy idea that having a PC with an analogue stick and 32 buttons could probably run Tie Fighter pretty well
-Light Guns: I bought a light gun that I've never been able to get to work quite right.  The driver test works, but then in mame it's a combination of the calibration being off, the offscreen reload not working, or the PC I have in there just not cutting it (Area 51 crawls).  More testing should sort this out.
-PC Upgrade: Now that the cabinet is pretty much done, the PC in it can really stand to be upgraded.  

You can see more photos at http://picasaweb.google.com/chris.bardon/MAMECabinet#