I discovered these online classes in just about any software imaginable. I was looking to improve my Painter 7 skills and took the entire course. It's called VTC and each course costs $99 but what is cool is that for every course the first 3 chapters are free. (No purchase necessary) Go to this
and click on any title and check out the free Quick Time tutorials. Even in the basics there's valuable info you may not be aware of.
Here's a real good one. Scroll down to Adobe Photoshop Special FX or Adobe Photoshop Advanced Techniques
and you will really get some great free tutorials.
I took the entire Painter 7 course and found it extremely informative. There were 12 hours of video and I really learned alot more than I could've on my own. Actually, I was amazed at what all Painter can do.
Whether you purchase it or not this site is an excellent resource and if you do purchase it, you get an aweful lot for your money.