Open Source for Mac OS X

Pixen is an innovative graphics editor for the Mac. It's designed from top to bottom for pixel artists—people who make low-resolution raster art like the sprites you see in old video games. But it's great for artists of all arenas: Pixen is like a very powerful MSPaint or a simpler, more agile Photoshop. And best of all, it's Free!

It utilizes a basic interface similar to that of Adobe Photoshop. While common tools are included in Pixen, such as the pencil, eraser, and fill tool, Pixen also uses a unique left/right tool system. This system enables the user to assign a different tool to the left and right mouse buttons. This can be used effectively when drawing and erasing. It also features several color palettes, as well as integration with Mac OS X's color options. Like many other bitmap-based applications, Pixen has a layer system that will let you organize parts of an image, name them, or hide them.