This could be fun – This site offers a wide selection of flashlight components for the DIYer in the dark. Including power regulators, various lamps/LEDs, reflectors, O-rings, and other relevant hardware. – Link

Anyone ever tried them out or know of other good sources?

Update: Commenter Schill recommends hitting up CandlePowerForums to get acquainted with the ins and outs of portable lighting – Link

HOW TO – Make a windup flashlight