According to the second test on that page, I have a tendency to associate numbers with locations in space. That had never even occurred to me as a form of synaesthesia. Neat.
meerkat299, you'd probably have fun with this. There's one set of questions where they show you a field of 2s and 5s and you have to figure out what shape the 2s form in a second or less.
(The first test on the page, on brain gender, is pure bollocks. Almost all the questions have the same letter answer, and there's only 5 or 6 questions; hardly enough to establish definite tendencies in one direction or another.)