From Cygnus Software:
Fractal eXtreme (64-bit) is a fractal exploration program that draws pictures of the Mandelbrot set and other fractals on your Windows PC. It allows you to explore these fractals by zooming and panning towards interesting areas with your mouse or keyboard. In Fractal eXtreme, we have attempted to combine speed, power, and simplicity with a few unique features -- all designed to make it easy for you to discover uncharted regions of the Mandelbrot set and many other fractals. Fractal eXtreme was originally written to make use of multi-processor machines so it can make full use of today's dual-core, quad-core, and many-core systems to dramatically improve calculation speeds.