I recently started using Neocolor II water-soluable wax crayons. This is a discussion of issues I have had with using the Neocolor with a waterbrush + a normal sketchbook.
My Flickr Neocolor Photoset
Last month, I went to Wet Paint and got some Neocolor II crayons. A man at the store told me that I would definitely also want a water brush. He was so right. I immediately fell in love with the crayons + waterbrush.