I have posted this before and will probably post it again. Optronics Competition Driving Lights, models QH-7CC and QH-8CC make just about perfect bike headlights. They are small, light, cheap (about $17/pair), easy to mount, and use easily available MR16 halogen bulbs. The come with a 50W bulb, but a new bulb of your choice only costs $3-10. I have never found them in an auto parts store, but Optronics will sell them to you. I prefer the black plastic model (QH-8CC) because it looks right at home on a bike, but the chrome metal QH-7CC is fine, too, if you want something a little retro looking. Either looks better than most of the Malibu lights I have seen.

http://www.optronicsinc.com/competition.htm

FWIW,
Raymond