For serious "night riding" (off road or when I will need to actually see the road) I like my Night Rider lights. These all have the rechargeable NiMH batteries. I like both a helmet-mount and a handlebar mount. Off road you need both for depth perception and to see around corners. Also nice to have two battery packs in case one runs low. On the road you can use you helmet-mounted light to uhm let motorists know you are there (as in shooting a beam of light in their eyes to stop them cold).

On days where I just think I *might* run a bit late I tuck my Petzl ( I have the Tikka) in my jersey pocket. It's good enough to get me home and makes me more visible to cars. It's not strong enough to really let me see the road or trail well though. I just strap it around my helmet. I also carry a bunch of those tiny Pyramid blinky-lights(Cateye makes some too) in both red (rear) and white (front). They are pony-tail elastics and can be strapped anywhere on the bike/body. I like on mounted on my helmet as well.