A friend showed me this website before... it's really helpful for graphic and web designers like myself, but there are also a bunch of Zbrush, digipainting / photoshop tutorials that might help a bunch of people out here too... particularly in the Tutorial and Inspiration sections of the site.

http://naldzgraphics.net/category/tutorials/
http://naldzgraphics.net/category/inspirations/

Hope it helps. Cheers. Check the other sections there too.