Jeff B.,
It's funny you mention irrigation. Thompson created some beautiful contour at Highlands Links, during the late 1930s, by burying rocks in the middle of fairways.
When the course's first watering system was installed during the mid 1990s, the irrigation contractor nearly went bankrupt. No joke. The job took much longer than originally anticipated, and I imagine some equipment was damaged too!
Adam,
Most important consideration when creating "uneven lies"?
Drainage. 99% of artifical contouring involves directing water to places where it won't puddle, or cause other problems.