Little did the computer graphics expert know that his HousingMaps.com, which combines a Google map with house listings from the popular Craigslist community, would be the start of an Internet phenomenon. Although Rademacher created his site about two months before Google publicly released its application programming interface -- the secret sauce that allows developers to create their own recipes with its maps -- the company wasn't angry.
In fact, Google hired him shortly thereafter.
"Now we see that all along there has been a huge amount of interesting information tied around location," Rademacher said. "Before, they had no way of expressing that and doing anything useful with it."
With such "mashups" -- hybrid software that combines content from more than one source -- digital maps are quickly becoming a centralised tool for countless uses ranging from local shopping and traffic reports to online dating and community organising, all in real time and right down to specific addresses.
Online mapping is evolving into a historic nexus of disparate technologies and communities that is changing the fundamental use of the Internet, as well as redefining the concept of maps in our culture. Along the way, map mashups are providing perhaps the clearest idea yet of commercial applications for the generation of so-called social technologies they represent.
They are, in a very real sense, bridging the gap between the virtual and physical worlds.
"This information has been on the Web for years," said Mike Pegg, a Canadian programmer who runs a site called Google Maps Mania. "The map is all of a sudden bringing this information to life for us. I think it has inspired a lot of people."
So prolific has the mapping movement become that Pegg has dedicated his site to documenting the staggering growth of mashups. He estimates that at least 10 mashups are created every day, each providing data that pop up in info balloons from the digital pushpins dotting various online maps.
Not surprisingly, this unprecedented interest is forcing change at old-world cartography institutions. Just last week, Rand McNally announced a new online mapping service of its own called MapEngine, which will allow businesses to integrate maps, directions and location search functionality into their Web sites. But such established companies will increasingly compete with free applications that have sprung up organically on the Web.
Already, hundreds of mashups overlay maps with everything from such practical information as petrol prices, hurricane movements, hot springs sites and crime statistics to the more entertaining if not frivolous, including photos of urinals, UFO sightings, New York movie locations, taco trucks in Seattle and Hot People by ZIP Code, a mashup of Google Maps and the HotorNot.com Web site.
This wildfire popularity has touched off feverish competition among the major portals that provide mapping services, especially since Yahoo, Microsoft's MSN and Google all released their map programming software to the public. But another reason cited for the boom in map mashups is one of hardware, specifically the processor speed and storage capacity needed for satellite photos and other resource-hogging images.
"They are taking off because the hardware has gotten to the point where it is possible and the software has achieved a bit of maturity, especially with Google Maps," said Rich Gibson, co-author of the book "Mapping Hacks." "Until very recently you couldn't effectively do mapping work on a personal computer."
Hardware and software aside, however, it is the ability for anyone to add information to a map that is increasing the usefulness exponentially and has inspired the mashup wave.
A case in point is Gmaps Pedometer, a widely distributed mashup that records distances travelled during a running or walking workout.
