[ Link page is under construction. I apologize for inconvenience. ]
A site with reference material intended for 3D modelers but more useful for artists because it has a collection of works by Andrew Loomis, illustrator and author of some of the best books on drawing. Loomis had produced five textbooks, forty years out of print but still unparalleled. Check them out.
Home of Worldtree RPG, a role playing game system and universe which I made some illustrations for.