With the start of autumn almost upon us, the daylight hours are getting fewer. Unfortunately, with increased hours of darkness, crashes
like the one that killed David Perkey are more likely when cyclists are out in the dark. He was apparently hit by a hit-and-run driver, and subsequently killed. While hit-and-run is never acceptable, the report states that he was riding without lights or reflectors. It's possible to ride safely in the dark, provided that proper equipment is used. More important than what lights to have, is to have
working front and rear lights to begin with. Reflectors and other reflective gear is good, but they by themselves are not enough. They only are visible when light is directly shining on them, whereas an actual light shines regardless.
Headlights are typically mounted on handlebars or atop one's bike helmet. Some cyclists prefer to have both. They range from cheap "be-seen" sorts of lights, all the way to extremely powerful (comparable to car headlight) systems used for mountain biking. Taillights typically mount on the seat post or rear rack, although there are also bar end taillights available. The latter may provide a sense of width to traffic. Numerous flash patterns are available, although I personally feel that the vast majority of flash patterns are "cute" but don't really add to safety. Since one cannot readily tell if a rear light has failed, it's preferable to have at least two rear lights for a degree of redundancy.
So, what lights do you use and recommend? I use a converted 2AA cell Maglite (with a 140 lumen LED mod from terralux) mounted with a twofish lockblock for my front light, and a planet bike superflash for the rear. Being somewhat interested in electronics myself, if people would like to learn about additional details about bicycle lighting, I would be glad to provide a primer. But ultimately, having working lights for all (street lights, reflective clothing, and reflectors are never enough) is way more important than what specific lights to have.