Here are a few sites with a large number of tutorials that I would like to see linked to on the wiki - but unfortunately, I simply don't have the time to tackle them all. If anyone here does have some time for these, by all means go through them and embed links into the relevant parts of the wiki.
[http://www.gimp-tutorials.com/] - a large amount of tutorials for the GIMP
[http://www.bluesfear.com/tutorials.php] - digital art tutorials
[http://www.niloufer.com/tutorial.html] - links to traditional drawing and painting tutorials
[http://www.knowledgehound.com/topics/art.htm] - all sorts of art
[http://www.artshow.com/resources/] - all sorts of art
[http://www.artgraphica.net/] - traditional drawing and painting
[http://www.elfwood.com/farp/art.html] - drawing and painting tutorials at Elfwood