O.K. so I started this trek with a Mame cabinet idea which isn't built yet, but I'm selling this idea to my wife by saying I can build her a jukebox after the mame cabinet. I like the touch screen idea. How much would I pay for the touchscreen and adapters to hook it up to a computer? Is there a link somewhere you guys can share?
That's exactly how I sold mine to my wife... LOL
As far as adapters, most touchscreens are really just regular PC monitors with a touchscreen overlay, so they'll have a VGA or DVI connector for video and a serial or USB connector for the touchscreen data. When the drivers are installed, it should just act like a mouse. The mouse data reports absolute directions only, so applications which measure mouse movement will have trouble (usually DirectX apps), similar to a lightgun.
As far as cost, a quick check on eBay will give you lots of options. It's worth noting, however, that touchscreens in 19" size or higher can get real expensive real quick, and you're already going to have a panel full of perfectly usable buttons. Also, with a touscreen you can't put glass or plexi in front of the monitor as you would normally have on an arcade cabinet.
--Chris