We have a closet that is unbearably dark. So I kept my eyes open for a light fixture that could do the job. I was pleased to find some white LED cove lights by Philips Color Kinetics that were being thrown away (Model: eW Cove MX). The lights are rated 100-277Vac, 13.5 watts each, are about 1 inch wide and 12 inches long and can daisy-chain together. Although these lights are designed to be hidden in a cove to provide an indirect glow to a ceiling or other architectural element, they work great lighting up a closet.
I mounted three lights end-to-end on a pre-painted piece of pine that I had. The lights allow themselves to be rotated for aimming after mounting so I pointed two downward and one upward. The board with the lights was mounted just above the door molding on the inside. I plan to permanently wire the lights to a switch outside the closet but that is another day's project so I spliced on a power supply cord and plugged it into a power strip. The closet is unbelievably bright using just over 40 watts of power!