Princeton Tec makes some nice lighting products. We're big fans of their cycle lights and their Byte headlamp, for example. The Amp 1L flashlight is a capable little flashlight if you value waterproofness in a lightweight light.
The Amp is waterproof to 100 meters, and with a carabiner clip it can accompany you pretty much anywhere and be there when you need it. The 45 lumen LED runs for 72 hours off two AAA batteries. A built-in bottle opener lets you pop a chilly one at the end of your epic.
The Amp is not so much an everyday light, since it requires two hands to operate the twist-to-activate head. There's no adjustable level in the lighting either, but hey, that's not why you bought it right? If you need an inexpensive, waterproof work light, check out the Amp 1L.