A few weeks ago I found this Citadel touch-screen. These units were purchased used from a major freight company. Inside the box is 386SX with 4mb of RAM and a 1mb flash disk. The screen is a VGA compatible 640x400 mono amber plasma display with an IR touch-screen covering the front. The whole unit is mounted in an extremely rugged steel case, weighing in at about 15lbs, which the main-board/screen can be removed from to save space and weight. Externally the units have one serial, a parallel, 5pin keyboard and a floppy connection.
Internally the main-board is attached on stand offs to the rear panel. The units come with a token ring card installed in the single ISA slot. You can replace the TR card with an Ethernet adapter or an ISA riser card (to gain more slots). One of my units has a laptop ide connector, the other has the holes but no pins. In the picture above is the one without, the empty holes are visible just above the 38pin floppy connector near the upper right. You can probably get a connector and solder it in for a $2-3 from Digikey if you want the harddrive. Plenty of space inside the case to stuff whatever hardware you want to add. The main-board has 4 30pin SIMM slots, populated with 1mb SIMMs. 4meg SIMMs can be installed to raise the total to 16mb RAM.
The display and touch-screen are installed in the front half the box. I've seen this sharp display several times before, so its probably pretty common. The touch-screen is attached to a controller that can be configured for 1200 or 9600bps and is wired to COM2 on the main-board. The touch-screen is polled by sending a '+' character, the reply is either a 'H' if no touch has occurred since the last poll, or a 'N' followed by two bytes (x then y) representing the coordinates of the touch.
You can purchase the Citadel Touchscreen online.