OVAT (Open Visual Arts Tool) is a very powerful image editor. It's interface is easy to use and highly configurable. You can use OVAT to edit photos, take screenshots, create texture for games, or anything you can imagine.
OVAT version 0.1.7 Pre-Alpha (Toolbars undocked)
OVAT version 0.1.9 Pre-Alpha (on Windows XP)
OVAT version 0.1.9 Pre-Alpha on Linux (by Thomas Calmant)
OVAT version 0.2.0 Alpha on Linux (by Thomas Calmant)
OVAT version 0.2.0 Alpha, showing a pic of Richard Stallman
OVAT version 0.2.1 Alpha on Linux (file browser)