I've found the Coleman 2AA flashlight with the tail cap switch to work very well. It's all aluminum, with some rubber grippy covering on the barrel and the head. Enough space for the luxeon star and a regulator in the head, too. It's green. You can find it at Walmart or online. (www.coleman.com???)
As roger said, the Coleman works well, and has the plus that it fits a stock LS (with the hexagonal board, not the square board) and still lets you use the reflector. And it gives you a nice thick flat mounting for the LS, which gives a good heatsink.