From popphoto.com: Free Photography Software: A Guide
There are certain programs that are pervasive in the photography world. For the most part, they’re the standard because they’re extremely good at what they do. But, there’s a a lot of photogrpahy software out there, and some of it is totally free. Apart from iPhoto (which you’ve probably already heard of), there are apps aimed at everyone from people who never take their cameras off auto, all the way up to those who only trust to shoot in RAW, and everywhere in between. In no particular order, these are some of our favorites.