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.
miniPaint - Online graphics editing tool use HTML5 technologies like Canvas, Offline support, Drag and Drop.
TwistedBrush Pro Studio - A powerful and unique natural media painting program.
RealWorld Paint - RealWorld Paint is an free portable image/photo/animation editor.
Corel Painter - Corel Painter is media painting software.
Paint XP for Windows 7 - Standalone old MS Paint program that allows you to get your old XP Paint interface in Windows 7.