Simple, yet powerful image editor
Red Pill provides the necessary tools to do high-quality image editing. It handles big images with ease -- as fast as Photoshop.
Red Pill is published as nagware. A nag dialog box appears after 7 application launches (not before!) that frequently reminds you to register and pay for the application.
Various brush types
Smart Fill -- removes object from image
Requires at least OS X 10.5; compatible with OS X 10.9 Mavericks