
Although a glowing keychain or lamp is impressive, they still fall short of the Iron Man minifig I saw for the first time at Brickworld 2008. Brickmodder together with Fine Clonier Decals turned a simple minifig into a shining, robotic version of awesome.
LED lights have been behind some of the most interesting LEGO MOCs (My Own Creations) in the past several years. LifeLites are LED kits that can power the internal lights of a MOC- like Joe Meno's Bond villain ray gun. LEDs are just AFOLs doing their part to go green.
Photo via The Brothers Brick.