Here's a brilliant piece about turning black and white images and video clips to colour with very little effort involved. You just scrawl a few lines and dots of colour on a mono image and some clever maths does the rest. Even more impressively do the same thing every few frames of a mono video and the maths extrapolates it across the whole clip - you'll have to watch the video clips to see how impressive this is.
The method can even be used to recolour coloured images - ie change people's clothes from red to blue. I've seen recoloured black and white stuff before and it always look over coloured - this method of doing it looks amazing.