Artist Cali Rezo does stunning artwork in photoshop- while she uses photographic reference for her work, she doesn't use it in her work. Although I've been know to throw a photo I like into photoshop and hitting the "dry brush" filter and call it a day, Rezo takes a more labor intensive approach. Rezo does all her work with an electronic pen and wacom tablet. You can see the results of these labors of love on her site, but even more valuable to our art classes are the flash videos that she has created of her works in progress. On her "Making Of" page, you can view her digital paintings grow out of sketches. It's not exactly a tutorial (despite my tag), but something clicks in my mind whenever I watch an artist put a painting together. Check out Rezo's process - these are the kinds of things I'd want to show my students when introducing them to painting (digital or the more traditional kind).