Mandelbulber is a renderer for 3D Mandelbrot fractals like Mandelbulb , Mandelbox, Bulbbox, Juliabulb, Menger Sponge. Its author, Krzysztof Marczak produces some of the most stunning fractal images currently on the web as well as spectacular videos using Mandelbulber :
Mandelbulber takes advantage of multi-core CPUs and its 64-bit version allows to produce very large images. A very powerful software which is worth investing some time in its non trivial user interface. But since it’s open source (C++), Mandelbulber may become more user friendly in the future and, who knows, use GPUs for computation one day.