My boys got some 2xAA flashlights for XMAS, Nice rubber coated ones. Because they always leave lights on, LED was inevitable. I have a bunch of 10mm in different colors I got off EBAY. I broke the glass part of the original bulbs and scraped or the remaining glass. I then made a few different types. I has a Super Flux Spider yellow resistored to 60mA, Negative leads just soldered to the top of the flange. 1 has a 10mm green running direct, this one draws 10mA, and is sufficiantally bright for my 2 year old. I also made a 10mm red and orange, each running at 20mA. My 10 year old likes these because he likes to read at night. The 10mm LEDs have a nice focus, about 1' spot at 3 feet. The yellow has a 140degree output and uses the reflector.
I have found out that flashlight for kids don't have to be white, they don't understand the 'coolness' of white LED's. Yellow and underdriven green are just as much fun for them.
Jeff