NDOThis is a powerful photoshop plugin for creating normal maps. This was free then became a commercial project. The free one can be found here, but i think the commercial project was taken down. The author’s website is here and a tutorial is here.
NormalMapperThis application find the dfference between hi-res and low-res models and output the difference in normal maps. Link here.
NormalMapper(AMD)AMD seems to have a normal map generator with the same name. It’s not in development anymore, but its still available for download.
SSBump GeneratorThis is a free tool for making self shadowed bump maps for valve’s source game engine
Normal Map GeneratorAnother free tool for making normal maps. Made by the same person who made the SSBump Generator. This one makes it easier to batch normal map coversions
ShaderMapThis is a commercial software. It makes professional looking nomal, displacement, specular and ambient occlusion maps. You can visualize your normal maps on models in it as well. It also comes with an SDK for some reason :/. You can download the demo for free.
xNormalanother software for baking normals from hi-res models to low-res ones in to normal maps
MindTexCommercial, but you can try it free for thirty days
CrazyBumpThis is a popular one, and my personal favorite . It’s commercial, but comes with a 30 day trial but for its beta version. It generates normal, displacement, specular and AO maps like ShaderMap.
Gimp Normal Map PluginThis one has free written all over it. You can generate normal maps right after drawing them and preview them on models. link