Miniature engineering at its best
Not strictly a bike light but we've included this because everyone needs a handy chuck-in-the-pack/around-the-camp light
What you get for your money is the excellent 3W Luxeon LED built into a tilting head unit and powered by four AA batteries.
This small, bright LED is so well thought out that it's a wonder no-one had thought of it before. The unit simply clips into the helmet strap and sits snugly around the temple area of a modern helmet. Compatibility with three different brands seemed good (although a challenge on helmets with an integral sweat/insect net).