The Minecraft farlands are a 3D Implementation of the mandelbrot set of complex numbers flattened and centered at y=0 such that x and z are the two inputs.
That's trippy as hell. The recurring patterns aren't a glitch, they're coded, and they're somehow based on the same repeating patterns that you see when you type "Mandelbrot set zoom" into youtube.
http://www.youtube.com/watch?v=UC17MxP9b0A&t=839