I like to see and be seen! Winter commuting has it's hazards, and darkness is one of them at this latitude. Perhaps I go a bit overboard, but I really like being able to see where I am going on a dark road in the rain.
I have a dynamo light (old bottom bracket generator), a cateye LED light and a cygo-lite battery-halogen set (on this particular bike). Planet Bike Superflash on the back!