Photo manipulation and image design
ColorPic - http://www.iconico.com/colorpic/
Pixia - http://www.ab.wakwak.com/~knight/
Sodiodi - http://www.sodipodi.com/
The Gimp - http://www.gimp.org/
Tuxpaint - http://www.newbreedsoftware.com/tuxpaint
Paint.NET - http://www.eecs.wsu.edu/paint.net/