I'm right in the middle of doing it from scratch.
I got two small LED arrays off
http://www.dealextreme.com/details.dx/sku.3873. I've run cable from the battery, along under the car to a 4x fused terminal box mounted under the car alongside where various other relays are sitting (probably for rear lights).
Reason for the fuse box - I've got accessories power running to two terminals and straight through power running to the other two. Have installed a flush mount accessory socket in the rear tray above the left hand guard. And I am installing two 90mm 55w lights in the two circular cut outs in the rear bumper to give me a bit more light while reversing (as others have done).
Finally I'm putting the two LED arrays in the underside of the hard cover. I have made a switch box with voltage regulator (so I don't kill the LEDs with overvoltage) and am installing a plug/socket at the front of the tray to unplug each time I remove the cover. Cable comes through a drilled hole in the front of the tray (near the left hand tie point as that's the only part I could access due to the liner).
I'm only doing it this way because I was running power down the back anyway - an easier way would be to go to Bunnings or somewhere similar, by one of those circular stick on LED lights and stick them to the underside of the tray - you will have to replace the batteries once in a while but it saves a lot of work in the long run.
Will take pictures once I'm finished (maybe this weekend). And will upload a circuit diagram too if anyone is interested.