Verve Painter!

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).

Clip Studio Paint, previously Manga Studio or ComicStudio in Japan, is a family of software applications for Mac OS X and Microsoft Windows used for the digital creation of comics and manga.

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.

Seashore is an open source image editor for Mac OS Xs Cocoa framework. It features gradients, textures and anti-aliasing for both text and brush strokes. It supports multiple layers and alpha channel editing. It is based around the GIMPs technology and uses the same native file format.

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.

Artweaver is a simple Freeware program for creative painting, i.e. Artweaver offers you all artistic effects which you need for your work.

Drawpile is a drawing program that lets you share the canvas with other users in real time.

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

GPS (aka Gimp Paint Studio) is a collection of brushes, patterns, color gradients, accompanying tool presets and dynamics. Tool presets are a simply saved tool options, highly useful feature of the GIMP.

Livebrush is a drawing application. It employs an easy-to-use brush tool that reacts to your gestures through the use of velocity and other motion controls. By combining simple motion controls with customizable brush styles, Livebrush offers a fun and unique way to create graphics. You can install Livebrush on Mac and Windows though it requires Adobe AIR.