I have some 3W amber LEDs arriving sometime in the next couple weeks. Initially the intention was to use them as daytime running lights because they're more visible than white during the day and would be as effective as a 'be seen' light with less power. No intention of dropping the white LEDs - the ambers would just supplement them for night-time use.
But I was thinking that in day-time city traffic, mounting a pair on the back and hooking them all up to a flasher would give the equivalent of hazard lights. Perfectly legal for a slow moving vehicle and an alternative to a stack of red blinkies.
These babies were a little tough to dig up. Is there some compelling reason that all LED bicycle lighting is red or white, but that reflectors are made in red, yellow and white?