PixBuilder - Free Photo Editing Software for PC
Sketch - Professional digital design for Mac.
showFoto - ShowFoto is the standalone image editor of the digiKam project.
Inkscape - Inkscape is a free, open source professional vector graphics editor for Windows, Mac OS X and Linux.
Fotografix - In addition to being totally portable, Fotografix has a ridiculously small footprint.
Adobe Photoshop - Adobe Photoshop is a webtop application for editing images and photos online.