The rolling high plains east of Colorado Springs (map) saw plenty of change before the "landmen" came. Ranchland that once stretched three or four miles between homes filled in with residential developments on multi-acre lots, bringing more people and paved roads.

Then, about two years ago, came a rush of real estate negotiators, snapping up leases for potential shale oil drilling. "I've never seen anything like it," says Rick Davis, 53, whose grandfather started buying ranchland in the early 1900s in Colorado's eastern El Paso County.   "Turns out that land was right in the center of all the activity."

And it has thrust the Davis family into the middle of a boom in U.S. oil production. Oil exploration is moving to