CGArena has a free tutorial from Matt Skenichi showing how to create displacement maps in Maya 8.5.
Randall Hand
Randall Hand is a computer graphics programmer and news junky that's been working in the field for the last 15 years. He's responsible for visualizations generated on some of the most powerful supercomputers in the world, ytnef, mullion support in ParaView, and VizWorld.com.
i have never seen this maya tutorial but i must say it’s relly good