How about a "retaining wall" site tool that would both illustrate a retaining wall (we could do boulders, block, concrete, timber...) and would establish the change in elevation based on the wall geometry we build. We'd need to be able to control how far the wall steps back (IE, block steps back at a slight vertical angle, boulders at a more gradual angle, and concrete is basically vertical) and we'd need to be able to blend the lower and upper surfaces together based on the length of the wall. The wall would need to be straight or curved, and we'd probably need to sketch the top profile to determine how the upper and lower areas blend together.
It would need to make the toposurface change to conform to the wall we build.
(Taken from this thread: http://forums.augi.com/showthread.php?t=8825)