Krita is a free, open-source platform that has quite a wide variety of tools/capabilities and is used a lot by people who don't have the cash for things like Photoshop, etc.
I use Artrage, Krita and Rebelle quite a lot. Krita is a free, open-source platform that has quite a wide variety of tools/capabilities and is used a lot by people who don't have the cash for things like Photoshop, etc. I use it the least, but it's pretty decent.