In case of emergency, there's always techniques based on the inverse FFT. If you fill a 2D image with white noise and then run an inverse FFT on it, you get the basic fBm fractal. If you shape that noise, you get other sorts of effects. Such surfaces also have the nice property that they tile. A good IFFT implementation can be a fair amount faster than some of the noise-based spectral synthesis techniques.

http://people.cs.kuleuven.be/~ares.l...ELPZ10SPNF.pdf is also a fun and useful read.