Wikipedia refers to white, red, orange, green and blue cats' eyes as being in regular use in the UK:
http://en.wikipedia.org/wiki/Cat's_eye_(road)
It's debatable as to whether the regular 'orange' cats' eyes are a different colour to the solar-powered 'amber' ones. (To me, one is definitely more 'yellowy' than the other, but I can't remember which way round it is!).
Similarly (even though they're not mentioned on Wikipedia) I've come across solar-powered 'white' cats' eyes which are more of a 'steel blue' to my eyes.
It's also interesting to note that Wikipedia says that the use of solar-powered cats' eyes has been suspended. There seem to be plenty of them (or at least some form of 'powered' cats' eyes) in use here in East Anglia (and in Kent).
Chris