I really like this little light. http://www.rei.com/product/807968/cy...usb-bike-light. No wires and lightweight, but a little pricey.

Very even and bright pattern (never have complaints re blinding), multiple output levels, has helmet and bars mounts, and runs a long time. Some people have complained the light mount is too tight, but it's easier to get the light on and off after a few weeks of use.