I recently sold my arcade cab I made as it was taking up too much room and I needed a more slimline unit so here's what I'm attempting to do:
An arcade/media hub with Nvidia 3D Vision for 3D Gaming and movies complete with touchscreen (still waiting on the Chinese to sort me out with a touchscreen overlay - I can only seem to get it from China but they are a PITA to contact!).
Controls will be via an old skool Competition Pro joystick for the old games and Xbox360/Wiii controllers for the newer games.
The monitor will have a touchscreen GUI which allows the user to select a variety of applications, these will be:
Jukebox (loads up jukebox and I will have a switch for speakers in garden or just indoors)
Arcade (will load Hyperspin, virtually every system you can think of except Xbox360 and PS3)
Videos (Not sure what I will load for this, possibly a lite XBMC)
Internet (Probably Firefox)
TV (will load WMC, that is until I get a DVT card that I can run on linux and then I'll merge TV with Videos and have it all in XBMC)
Radio (Not sure, open to suggestions for radio stations - might just make my own touchscreen radio station guide)
Apps (This will load up a touchscreen menu created with simpletouchfe showing all the Windows apps)
I will probably add some more but for now that's the basics. I'm also going to attempt to hook my main TV up in the lounge as the second monitor via HDMI and have XBMC on there constantly with audio coming through HDMI so it doesn't interfere with audio on the other monitor.
So far here's my progress...
Make base out of MDF

Add a support rail for lid which needs to be removable (the lid not the rail!)

Completed Base Unit

Added monitor support

Wall mounted monitor and added wall hooks for peripherals

Added fans, Left = blowing in on PC, Right = pulling air in for Arctic Cooling, Middle = PSU exhaust:

Added all the PC components - they just about fit, that was lucky! Sorry for the blurry pic on this one:

Added a fan to the corner of the lid which blows the air out of the unit and up behind the panel hiding the wires behind the monitor - giving it a chiminey effect. The panel will be painted the same colour as my walls so it's not so obvious.

Needs a paint job (a glossy black finish needed) but it's getting there...

So it's all plugged in and ready to test, however there was one quite big flaw in my plans... I forgot to buy a button. How can I switch it on without a button? DOH! I can't even find anything that would temporarily do, oh well I'll have to think about a button on Saturday now.