Krita is an free opensource digital painting app, you should check it out and help shape its future
I don't know about you, but I barely scratch the surface of photoshop features, they don't seem to apply to what I like to use photoshop for, digital painting. I've always been kind of let down by its lack of focus in this area. It gets the job done but still I'm always keeping my eye out for something that works better and Krita might be it. So far I really like it and I like that they are open to community input. It's a little light on features but that's where we (the community) come into play.
Since it's free you can try it out and see how you like it, offer up your 2 cents and if you want to help expand it they have a KickStarter campaign going.
Get Krita 2.8 (for free)
Thanks Ponk for letting us know