When I was a kid I loved to check out drawing how-to books from the library. Some of my VERY favorite books were those put out by Ed Emberley. (Click his name to be directed to his fabulous website where you there all sorts of fun activities!!)
He had several book that were based on colors (Big Purple Drawing Book, Big Green Drawing Book, etc.) He including everything from cute little animals to intricate pirate ships. I remember pouring over them and drawing all sorts of environments and creatures.