L3DT - Large 3D Terrain Generator

L3DT is a terrain or heightmap generator that can be used to generate heightmaps for game design, it also can generate base diffuse/normal/lightmap textures or layer maps, so it can be imported easily into Torque3D.
There is a free basic version and a paid professional version, the basic one is enough if you just want to play around, the professional offers some more features and a seamless direct import into Torque3D.