Some
freebie photo editing programs:
GIMP
(very powerful, comparable to PhotoShop)
GIMP - The GNU Image Manipulation Program
Photoscape
(lots of cool filters, very different from others, you'll probably either love it or hate it, does animated GIFs)
PhotoScape - Free software downloads and reviews - CNET Download.com
PhotoPlus 6
(I have used old versions. Very basic. Easy to learn. Not very powerful.)
Free Image & Photo Editing Software Download - PhotoPlus
IrfanView
(better as a fast viewer and organizer than editor, make sure to get all the plugins)
IrfanView - Official Homepage - one of the most popular viewers worldwide