It has been compared to the video game SimCity, but at $4,995 a pop, CommunityViz 3-D simulation and modeling software is no toy. More than 100 communities have used it to develop and lobby for land plans, says the product's developer, Boulder, Colo.-based CommunityViz.

Steamboat Springs, Colo., used it to forecast affordable housing needs and gauge the economic impact of luxury development.

Fearing Twin Cities sprawl, rural Eureka Township, Minn., completed a two-year modeling of six land-use scenarios.

The nonprofit 1000 Friends of Minnesota operated the software for that project and a concurrent one in Franconia Township. "It might not be the builders' best friend," says Molly McCartney, the growth watchdog's land-use planner, "but it could help builders because you won't waste time with proposal 'A' when the community wants proposal 'W.'"

Remi Stone, public policy director for the Builders Association of the Twin Cities, says such projects "draw people into the development process earlier, and that usually makes things go more smoothly."