I use GIMP or the GNU Image Manipulation Program. It is FLOSS (Free Libre Open Source Software) meaning there's no price attached to it legally. It is an alternative to photoshop. If you don't feel like illegally downloading PS but want to create sigs/avitars/images this is the program to get. It is cross platform meaning it can run on Windows/Linux (not sure of Macs). anlgp's gimp Bookmarks on Delicious there are some resources I've delicious'd for it.
