I've got some more goodies for you! These are some fun programs. You can use them to help you get over artists block or create some amazing masterpieces with them. Have fun!
This a free web-based program that is basically a blank canvas. You have certain elements you can use such as sketchy, shaded, chrome and fur. What I liked about it is the fact that I can use it to help with artists block. As a writer might use stream of consciousness writing (or free writing) to get past a block, I can use this to just sketch away. Most items might be jibberish and not worth saving, but when you do come up with something good, you can save it.
MyPaint is fun. It's a light-weight program with brushes. I use my tablet and pen with it, but you can use a mouse and keyboard. It feels like painting. The same techniques you use in "real life" painting, you can do with the digital painting. The brushes can be made bigger or smaller, more opaque or translucent. I like that you can have it open side-by-side with a reference picture. It doesn't take a lot of space for the tools.
Did I mention both are free? :)