It's fun to brag when you're at a great bar or going off on vacation. Social networking sites and location-based apps have made it easy to broadcast that kind of information to your friends. The problem is that you may not just be making your friends jealous, but supplying criminals with useful information as well.

A new Web site called PleaseRobMe.com has drawn attention to the issue by repurposing posts from foursquare, a social networking site that lets people share the latest about their whereabouts. PleaseRobMe demonstrates that it's easy for anyone to find out you're not at home — and therefore, are presenting an "opportunity" for burglary.

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"What seems like an innocent pass-off of information to a small number of friends can be useful for bad guys to exploit," says Lee Rainie, director of the Pew Internet & American Life Project.

Last year, a "bling ring" of four teenage girls and a man were arrested for allegedly carrying out a string of burglaries targeting celebrities including Lindsay Lohan and Orlando Bloom. They were accused of using Internet mapping and gossip sites to case the stars' homes.

These days, you don't have to be a celebrity for criminals to connect the dots about your location. Posts and pictures give away all the information criminals need for learning when you're on vacation, whether you have a big dog and whether you own cars or flat-screen TVs worth stealing, says Nick Newman, a computer crimes specialist with the National White Collar Crime Center.

Rainie calls it the 21st-century equivalent of reading the obituaries. Burglars have been known to read obits to find out when funerals are taking place, knowing that the homes of loved ones are left unoccupied and unprotected.

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