I only realised I was doing it a year back perhaps, but every time I listen to music I get a strong picture in my mind based on the tambre, instrumentation and various other qualities of the piece. It's not completely random either- for example a square lead is always white, a triangle lead is always yellow, a french horn is always blue (although depending on how it plays, it can go light blue all the way to blue-green), a violin is a green-brown colour, again changing slightly on how it's played and so on.
It's not just colour, shapes form too until you get a whole, three dimentional image. From this I can remember exactly how a song goes, even if I can't remember how it actually sounds. It's also how I remember what to play if I'm doing live stuff.
Anyway, enough of what I see; I was curious to see if any of you 'see' music, and if so, what does it look like/sensations do you get? I can't be the only one right?