Yes, I run in the dark (I'm in the dark most of the time, so why not run?). From now until late March, usually two nights a week, my running will be on trails in the evening after I get off work. Distances vary from 6 to 10 miles, mostly trails, some forestry roads (lots of eyes looking back through the trees).
I rearrange my lunch time so I can do one or two daytime runs.
It is a common practice amongst trail and ultra runners. Some of our "organized, get a t-shirt, has aid stations" runs cause us to be out most, or all, of the night so we had better train for running in the dark (this is the source of Bruce Springsteen's hit).
The Ultralist question: Try Kevin Sayers' UltRunR Web Site
http://www.fred.net/ultrunr
It has a link to the Ultralist and more links and articles about running than you've ever wanted to see.