In 1979 an official Dungeons and Dragons coloring book was released. The illustration was done by Greg Irons. In addition to some wonderfully evocative illustrations there were also descriptions of various creatures and a write-up of a quick adventure that you could play. Over at Monster Brains Aeron Alfrey uploaded scans of the book. I've gone and downloaded the scans and made a single PDF file out of them using the free software Image to PDF Converter. Counting the cover and the back page the pdf file is 32 pages long. I'd love to see people scanning in their coloring and giving them to me so I can upload and share with others. Here's a link the pdf.