Picture by r0kk
The Craft At Home site details a basic recipe for chalkboard paint, which essentially involves adding powdered tile grout and glazing medium to the coloured acrylic paint of your choice. (Craft guru Martha Stewart offers a version that just uses tile grout if you don't fancy hunting down the glaze.) Darker colours are still likely to work better if you want to use standard white chalk, but with coloured chalk, the potential combinations are pretty much endless.
How To Make Your Own Chalk Board Paint [Craft At Home]