edit: I've just thought about it and that makes perfect sense. Using a grey card for WB has never popped up at school or work and I don't know anyone that uses a card for this purpose, not that I think it's a bad idea. Back to your question, I only know that some of the higher-end cameras do offer a manual define option for WB
atm I am only shooting digital with a D200.
I was trying to make a point with the analog part
edit: damm chucker your so fast at replying when i'm refining my post