Do you know a dead spot in your mobile phone network’s coverage? If so, here’s a chance to share it with the world. Signal Map Beta (their tag line is “Beta is an understatement”) allows you to see network coverage as reported by users superimposed on a Google map. You can zoom it, select all carriers or a single carrier, and add your expertise to the map (you are encouraged to do this, it’s easy and kind of fun.)

This is one of the more useful mashups I’ve seen.

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