Paintstorm!

Krita is a complete creative sketching and painting application with advanced, commercial quality features. It's free, open-source and available across all major desktop platforms.

MyPaint is a fast painting program with an emphasis on full-screen use. It lets you focus on the art instead of the program. You work on your canvas with minimum distractions, bringing up the interface only when you need it. MyPaint supports pressure or tilt sensitive graphic tablets and comes with an easy-to-use brush collection. There is a complex interface for creating own brushes, focusing on brush dynamics (changes with speed, pressure, randomly).

FireAlpaca is the image editor that can be used readily and easily. We made it possible to provide the completely free download, in order for our products to be experienced by more users from all over the world. It is available for both Mac and Windows users! We would like you to experience this great opportunity first.

Corel Painter is a raster-based digital art application created to simulate as accurately as possible the appearance and behavior of traditional media associated with drawing, painting, and printmaking. It is intended to be used in real-time by professional digital artists as a functional creative tool.

A simple but lovely natural media painting and sketching program. Art oriented, but capable of loading/saving photoshop files. A very cheap alternative to Painter, with a stripped down, elegant interface.

Infinite Definition. Mischief uses a revolutionary new stroke representation. Get the richness of pixel-based brushes AND the scalability of vectors. Zoom in to any size and get a PERFECT edge. Export at ANY size and resolution.Infinite Canvas

JugiPaint is a painting software with diverse sets of tools for various types of illustration work. It provides many standard digital painting features like layers, brushes, selections, transformations, etc., as well as some less often like guide layers and panels.

Sketches is a perfect mix of beauty, simplicity and power, a truly unique combination you won't find anywhere else.

openCanvas, popularly abbreviated as oC, is a popular Japanese image editing program.

PixelStyle Photo Editor 3.5.1 for Mac is an all-in-one Photo Editor for Mac with a huge range of high-end filters: lighting, blurs, distortions, tilt-shift, shadows, glows... Available at http://www.effectmatrix.com/mac-appstore/mac-photo-editor-pixelstyle.htm