All around 3D
Usefull tools just for 3D-Modeling and co.
xNormal is an application to generate normal / ambient occlusion / displacement maps. It can also project the texture of the highpoly model into the lowpoly mesh ( complete texture transfer, even with different topologies ).
It includes too an interactive 3D viewer ( with advanced shaders and realtime soft shadows / glow effect ), some Photoshop filters and importers/exporters for 3dsmax and Maya.
It supports high levels of parallelism using multicore/multithreading, distributed/parallel rendering, ray tracing and advanced GPGPU techniques.
GIMP Normalmap Plugin
This is a plugin for GIMP version 2.8.x. It allows you to convert images into RGB normal maps for use in per-pixel lighting applications. The goal is to completely clone NVIDIA's photoshop plugin, with a few new useful features.