Bangkok taxis tend to be green and yellow. Except when they're red and blue, although those tend to be a bit crap. (This is in terms of age and upkeep and ambient stinkiness. As far as the models go, 95% of them are Toyota Corollas, take it or leave it.)
In recent months, I've noticed a number of innovative, transgressive colour schemes, including vibrant orange and hot pink. But best of all are the new red ones with white stripes. I got in one of these the other day and asked where Huggy Bear was. The driver, of course, hadn't a bloody clue what I was on about.