GIMP means GNU Image Manipulation Program. It was first released in 1996 by two students from Berkeley University and it has been getting better and more widely used ever since. It offers all the basic and many of the advanced features of applications like Adobe Photoshop: layers, channels, paths, different painting tools, etc. Download the free application from www.gimp.org.
Today something for the more graphically advanced. I am not a Photoshop pro, but I've noticed playing around with brushes, textures and backgrounds is very enjoyable for me. They allow me to create compositions 100 times easier and faster and at the level I would never be able to achieve by using just the defaults in Photoshop. Download hundreds of free Photoshop brushed and have fun.
"Puppy Linux 2.15CE (Community Edition) is the result of collaboration between a team of Puppy Linux enthusiasts. It is built upon version 2.14, but includes many enhancements. In particular, the guys have worked on an improved user interface and a nice out-of-the-box first impression. They have also developed some SFS files that add OpenOffice.org, web and graphics applications; SFS files are 'combo packs' of applications that can be installed and uninstalled with a few clicks."