Essential Gadgets for Every Home Office

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The Square Lets You Make a Credit Card Sale Anywhere

This app and card reader from Twitter co-founder Jack Dorsey works on iPhones and Android phones. While this system is extremely new—it officially launched in February 2011—of all of the various available options, Square has the most straightforward system to accept payments and make money anywhere. Cost: The device is free, but there's a 2.75 percent transaction fee charged at the point of sale