I have seen one rider with a Radbot 1000 tail light on the wristband of his winter commuting glove. The Radbots have a good reflector and a good bright light. When he's riding, it's pointing down at the ground. When he signals, it faces back at traffic behind.
Personally, I think I'd find the flashing down at the ground annoying on a dark commute. But it might not be hard to fit in a tilt switch.