Krita - Krita is a professional FREE and open source painting program. It is made by artists that want to seaffordable art tools for everyone. Concept art. texture and matte painters, illustrations and comics.
TwistedBrush Pro Studio - A powerful and unique natural media painting program.
MyPaint - MyPaint is a fast, distraction-free, and easy painting tool for digital artists.
Adobe Photoshop - Adobe Photoshop is a webtop application for editing images and photos online.
Artrage - A simple but lovely natural media painting and sketching program.
GIMP - GIMP is a multiplatform photo manipulation tool.