The Neighborhood Gardens Association uses the NIS to assess gardens it is considering purchasing for its land trust. The garden group can collect information on a property's ownership, size, tax status and council jurisdiction.

"There was a window over the last several years where nonprofits jumped in to offer community information systems, and the cities are just now starting to catch up," he said. "Philadelphia has been a big supporter in sharing data because they're one of our biggest users."

Culhane said cities and counties also face liability issues about publishing erroneous information or wiki-style guides that may be inaccurate. Philadelphia spent five years updating its parcel layers, he noted, but city officials didn't build an application to show them because they knew there were errors in the data. Nonprofits like the NIS have more leeway, he said, to advise users that data may not be 100 percent accurate.

Some local government GIS departments are innovating with geospatial data for their own use.

In March 2006, the Technology Services Department of Johnston County, N.C., began field-testing a program that gives the county's planning and inspection teams GPS units attached to wireless data transmitters. That gave the inspection manager a real-time map of exactly where each building inspector is at all times, said Lori Key, GIS applications analyst for Johnston County.

"If a call for an inspection comes in, she can see which one is closest, call them and say, 'Go to 305 Henry Street,'" Key said.

With the GPS devices, inspectors also can record the exact location of a pothole or other problem the county needs to address, Key said.

The county is considering adding GPS devices to emergency response vehicles so it could instantly generate helpful maps for the public in case of emergencies such as hurricanes. Key, who has been working in GIS since 1997, said the field has recently exploded. A few years ago, people in county government, including some of the commissioners, didn't even know what GIS and GPS were.

"But now that they've seen what it can do, they're asking about its potential for use in other areas of county government," Key said. "It's an exciting time."

David Raths  |  contributing writer