The green ones were usually for colour work. We never had one at university (the last time I had a really good darkroom) because they do actually fog colour materials, they're just so dim as to make fogging tolerably slow and are pretty useless for actually seeing anything. We did colour stuff in total darkness; it's not that hard, although getting the paper perfectly straight under the enlarger takes a bit of practice.
I don't think anyone's tried it, but a bright infra-red safelight could work for many people yet be completely safe for all film except actual IR film. A lot of people can see IR; it's just drowned out by the much greater sensitivity to visible light. It's probably hard to filter out the last of the red visible light, though.
