I know I have mentioned the website Life Hacker a few times here. I check it every day and would recommend it to anyone who owns a computer and/or ventures occasionally out onto the internets. There was a post the other day that highlighted the favorite free software of the Life Hacker community. You can see that great list here.
A personal recommendation: We do not have access to a graphics program at the library, lord knows why, and I have the free program Gimp installed on my flash drive. It's like having a portable free version of Photoshop. It doesn't have all the bells and whistles but if you are doing some simple photo editing it is a great piece of software.
I am also a big fan of VLC Media Player. Screw Windows Media Player.