I'm a sucker for LED lights. I'll have to post a review of my little 3 watt and 5 watt collection sometime. But in the meantime, here are some geeky posts:
- Simple Luxeon LED bike headlight (el cheapo)
- 3 watt Luxeon bike light (very sophisticated)
- Home Depot headlamp (a classic)
- SingletrackWorld conversation about homebrew LEDs
They are also useful for photography. :)
If you're into bike equipment, Moe's is a blog with good deals on bike stuff: http://moesbestdeals.com/