Most people who have laptops stolen get angry. Joshua Kaufman got a Tumblr. The Oakland man set up an account on the blogging service called “This Guy Has My MacBook” and posted photographs of the thief using an application that allows owners to surreptitiously snap pics of users and track the computer’s location. Within hours, Oakland police contacted Kaufman—who tweeted the whole ordeal—and told him they were on their way to nab the thief. Soon afterward, he learned that both the thief and the laptop had been recovered.