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Map Mash-Ups
Even on the surface, it’s clear that Google Maps goes much further than older interactive map sites. The stunning satellite views, along with the ability to drag the map in any direction without having to wait for the page to refresh, are the most obvious advances. The shaded pop-up balloons pointing to the locations turned up in local searches – Google calls them “info windows” – are also a pleasing touch.

But it’s what’s under the hood that really excites programmers. Within hours of Google Maps’ release, programmers had reverse-engineered it, discovering that most of the interactive features relied on simple miniprograms or “scripts” written in JavaScript, one of the Web’s best-known languages for scripting. That meant programmers could write their own JavaScript to manipulate the maps – for example, making their own content, rather than the usual Google search results, appear in the info windows tied to specific map locations.

Almost immediately, programmers started building services atop Google’s map infrastructure. Computer graphics expert Paul Rademacher, for example, launched HousingMaps, a site that pulls real-estate listings off the popular classified-ads site craigslist, uses the addresses of the listed homes and apartments in a given neighborhood to figure out their latitudes and longitudes, and lets users view the properties on a Google map. HousingMaps has no affiliation with craigslist or Google; Rademacher built the hybrid site simply by figuring out how to write coded requests that would grab the appropriate data from the two companies’ public databases. Fortunately, the companies take a mostly benign view of such mash-ups.

Google is so eager to let outside programmers experiment with its mapping platform, in fact, that it released an official API on June 30, meaning hackers would no longer have to waste time on reverse-engineering. That’s led to an even bigger wave of Google Maps creations, from the practical to the disturbing. At, you can see gasoline prices from plotted on a Google map, directing you to the lowest-priced pumps in your area., meanwhile, shows place marks for the homes of every sex offender listed in the Florida Department of Law Enforcement’s public database. Clicking on a place mark brings up an info window with the offender’s name, address, and mug shot.

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