Official website: http://awesomebump.besaba.com/ (dead)
Mirror website: https://sourceforge.net/projects/awesomebump.mirror/
Awesomebump looks to be one of the best upcoming free alternative normalmap/material generators.
I have not tried it much yet, but it has a lot of features and looks like a good competitor to commercial software like Crazy Bump. It does not just generator normal, bump and specular maps but also maps compatible to the newest physically based rendering technologies, as well as some image editing functions helping you to make seamless textures.