If you have ever fancied putting your genius on the map, the latest online craze should be right up your street. In recent months, a new form of interactive cartography has reinvented the way we use digital maps. By mixing ordinary streetmaps with specific local information, hundreds of amateur cartographers have created some extraordinarily clever ways to visualise geographic information. From neighbourhood traffic flows to the quality of public urinals, these clickable atlases are offering fascinating new ways to portray the world in real time.

The maps are known as "mash-ups", a term first applied to recordings that merged two or more sources of music, as in DJ Danger Mouse’s Grey Album, a blend of the Beatles’ White Album and the hip-hop star Jay-Z’s Black Album – unauthorised, naturally, but nonetheless lauded for its creative genius. With maps, the starting point is typically a streetscape from Google, Yahoo Maps or Microsoft Virtual Earth. The mash-up takes place when the cartographic data is mixed with useful databases or just annotated by hand.

The trend is said to have been kick-started last spring by Paul Rademacher, a software engineer at Dreamworks Animation who worked on Shrek 2 and Madagascar. Rademacher, needing a home, found a way to combine property advertisements from the Craigslist website with images from Google Maps. He did not have Google’s permission, but the result, at housingmaps.com, quickly found its way on to thousands of internet bookmarks. Its utility was obvious: click on a city map, from London to Los Angeles, and you can navigate your way between properties via location, price or photograph. You can even scale the map to see where on a street a property lies.

Within a couple of months, Google released a free toolkit to encourage other techies to play around with its mapping service, prompting a wave of creative thinking. At weatherbonk.com, you can click on your local map to see the temperature, windspeed, even live traffic-camera feeds. If you want football results, esportiudigital.com, an online sports paper, presents UEFA Champions League results and fixtures on a scrollable map of Europe. There are mash-ups which geographically locate cars listed in eBay’s motoring auctions, maps that help you find a cash-machine, even one that takes photographs submitted to the "Hot or Not" website and presents them according to their owners’ home addresses.

Some of the most provocatively useful mash-ups are American, including those that map out Chicago’s murder scenes, San Francisco’s mobile-phone towers and Georgia’s sex offenders. But Europe is fast catching up. Start at GMdir.com, an unofficial directory of Google Maps mash-ups, and you will find annotated guides to Folkestone pubs, Dublin petrol prices and English speed cameras. Not everyone is amused. The hybrid that pinpoints the homes of Hollywood stars (at celebrity-maps.com) has been criticised for encouraging stalkers, while Craigslist has acted to prevent third-party sites profiting by mining its content. But for Paul Rademacher, the trend has only brought good news. Impressed by his unauthorised handiwork, Google proceeded to hire him.

david.rowan@thetimes.co.uk

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