gimp is a free piece of software which you can do all the things you can do in photoshop with the same sort of tools, such retouching, cloning and photo effects ect
gimp can work on the following platforms
- GNU/Linux (i386, PPC)
- Microsoft Windows (XP, Vista)
- Mac OS X
- Sun OpenSolaris
gimp can accept
to find more about gimp follow the link http://www.gimp.org
this is what the makers of gimp say about it found on the gimp website above
"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.
It has many capabilities. It can be used as a simple paint program, an expert quality photo retouching program, an online batch processing system, a mass production image renderer, an image format converter, etc.
GIMP is expandable and extensible. It is designed to be augmented with plug-ins and extensions to do just about anything. The advanced scripting interface allows everything from the simplest task to the most complex image manipulation procedures to be easily scripted"
picasa is another free software you can do basic editing to your photos and then upload them to the picasa site to show them off
to find out more about picasa follow the link
these are just a few of the free software out there, so have fun looking and using, for more information check out this page more information