The Gimp - " GIMP is an acronym for GNU Image Manipulation Program. It is a freely distributed program for such tasks as photo retouching, image composition and image authoring."
GNU
Gwenview - " Gwenview is a fast and easy to use image viewer for KDE."
GNU
ColorPic - Colour selection tool with lots of features.
Freeware
Irfanview - IrfanView is a very fast, small, graphic viewer.
Freeware
JAlbum - Free web photo album generator.
Freeware