White headlight and red rear reflector. That's the law.
When you pay dues for a Chicagoland Bicycle Federation membership they give you the choice of a map or a tail light. I have it on good information that CBF is going to switch from tail lights to head lights specifically to make their members more aware of and compliant with the law with respect to headlights.
I never understand why people ride without lights. Having been a driver I can tell you that there is nothing more invisible than a cyclists with no lights or reflectors. You wouldn't drive a car with no headlights; why would you think you could do the same on a bike?
Need a rear reflector? Just let me know and I'll hook you up with some red reflective tape.