I bike in the dark, in the rain, in the cold, all of that good stuff.
I also have a lot of lights. For the back, I have one on m helmet, one on my bag, and one on my seatpost.
I have 2 for the front.
Admittedly, I am a little paranoid that people might not see me, so I might have gone a little overboard with the lights.
What I don't understand is people who bike in the dark without lights, or anything reflective. Sometimes they have helmets, often none.
It's great that they're biking, but the sheer stupidity astounds me. Do they realize how hard it is to see them? Is there a death wish thing going on? Personally, I think it's very inconsiderate of others who might run them over accidentally.
There. I've ranted.
Oh, and don't get me started on fixie riders who go helmetless. Wear your goddamn helmet.