Tate Liverpool currently (until 13 September 2009) has an exhibition charting the history of colour from 1950 to today. As well as exhibits from Cory Arcangel, Donald Judd, Gerhard Richter (and many others), the Information Assistants’ colourful silk waistcoats were designed by Daniel Buren
There is an excellent and very colourful (of course) interactive website where you can play with colour wheels and do some digital painting by numbers. There is a also a dedicated Flickr group where you can upload your monochrome photographs. And there’s also a dedicated site for the kids with lots of colour related games.
Start exploring here.