FREE SOFTWARE
IRFANVIEW
A very popular free image viewer.
http://www.irfanview.com/

GIMP
A great and extensive open source Image editing program.
http://gimp-win.sourceforge.net/index.html

QTPFSGUI
A program for HDR high dinamic range photographs. Not the
easiest program to learn but it gives great results.
http://qtpfsgui.sourceforge.net/download.php

HUGIN
A program for creating Panoramas. Again not the easiest program
to learn but it gives great results.
http://hugin.sourceforge.net/

STEREO PHOTO MAKER
Program for the creation of Stereo Anaglyth 3D photographs.
http://stereo.jpn.org/eng/index.html