Filter Forge - On the surface, Filter Forge is just a Photoshop plugin, a pack of filters that generate textures...
Blender - Blender is the open source, cross platform suite of tools for 3D creation.
Crazybump - Texture map tool
Cinema 4D - Cinema 4D is a 3D modeling, animation, motion graphics and rendering application.
xNormal - xNormal is an application to generate normal / ambient occlusion / displacement maps.
ZBrush - ZBrush is a digital sculpting and painting software solution.