Although its probably not its intended usage...heres a tutorial for making a rock wall with Greeble...thanks to Tom Hudson for this great plugin.
A brief tutorial on how to do it:
http://www.dwayneellis.com/misc/fxw...Rock%20Wall.pdf
Some Screencaps:
(For some reason the links weren't showing up...heres the directory.)
http://www.dwayneellis.com/misc/fxwars/tutorial/
And the maxfile:
http://www.dwayneellis.com/misc/fxw...-RockWall01.max
Have fun!