Fraqtive is a multi-platform generator of the Mandelbrot family fractals. It uses very fast algorithms that support SSE2 and multi-core processors. It generates high quality anti-aliased images and renders 3D scenes using OpenGL. It allows real-time navigation and dynamic generation of the Julia fractal preview.
Picogen is a program to create, design, and render artificial 3D terrain scenes. It is currently not very nice to non-programming-end-users, as the heightmap definition is a program with a LISP-like syntax. It aims to be similar to the Terragen program and provide a free and unrestricted alternative to it.
NeoTextureEdit is an easy to use graph-based procedural seamless texture editor. NeoTexture is the associated run-time generation library. Using continuous basis functions, it can generate arbitrary resolution images without quality degradation. Its main purpose is to produce high-quality textures for real time rendering applications that can be stored in a few kB and synthesized on application startup. But it can also be used to generate off-line images.