Dilemma: I am not a classically trained keyboardist, i am more of a hunt-n-peck typer. I have one of those under-the-desktop keyboard trays but I can't read the letters on the keyboard unless i turn on every light in the room.
Solution: Mount some LEDs under the desktop and Voila! My problem is solved.
Step 1: Parts and Such
Get some LEDs (the ones i used come in a set of three wired together. I got them on ebay and didn't have a use for them (until now).
Get a 12Vdc wall wart power supply (or whatever other wall wart would work for you).
Get one of those little lever micro switches.
Some screws and such.
Step 2: Mount the LEDs
Find a place along the edge of the desktop to mount the LEDs.
These had sticky stuff on back but it was kinda not very sticky so I used some screws.
Step 3: Mount the Thing That Hits the Lever on the Switch
I had this little angle thingy which was perfect for the striker. Find a place to mount it on the back of the tray when it is in the closed position. It should clear the underside of the tabletop by 1/16" or so (1-2mm) but still hit the switch lever.
Step 4: Mount the Switch
Mount the switch so the lever is all the way in with the tray all the way back. It will click when it pushes in and released. I used some panel nails to mount it as it fit in the tiny holes in the switch. The bracket should strike the lever on the switch and click.
Step 5: Wire That Bugger
Take your wall wart and cut plug off. On mine, there were two wires, one with a white stripe. The white stripe wire is the positive voltage so wire it to the +12vdc of your LED. The black wire goes to the ground. I then ran both wires together back to the switch. Here I slit the wires apart and then cut the ground wire and soldered it onto the switch. The switch should be normally on when open and off when closed. (The tray is all the way in so the switch is depressed and the LEDs are off). You can see in the pics which terminals on the switch I used. Test to see if it all works correctly before soldering everything together.