Anyone who rides at night needs BOTH reflectors AND lights.
This tail light from Amazon comes well recommended for the price and has nice vintage style. I'd like to see if I could mount it on my fender, to add to the blinkie I have on my helmet. We will just have to work out how to secure the lens which apparently has a tendency to fall off.
For a more futuristic look, this other light from Amazon has an interesting look. I could see it on a bike with a more modernistic aesthetic. It almost looks Star Trek to me, and I like that about it. It is also nice in that it appears to mount with hardware. I suspect you leave it on the bike and that makes it hard to steal. Anything that makes your commute simpler is always a good choice.
The most interesting tail light at REI is this lollypop-styled light. They claim you can mount it anywhere. I like the customer's suggestions to add these to your bags. It seems like a light and easy way to get more visibility.