Back in the day, the search for little green men took time and labor. The truth might be out there, sure, but to find it one needed faith, ardor, a certain courage of convictionand, of course, plane tickets to Roswell. But since Berkeley's SETI (Search for Extraterrestrial Intelligence) program premiered its Seti@Homescreen saver, any Tom, Dick, or Harry with a CPU and a modem can scan the skies for signs of E.T. After the app is downloadedfrom setiathome.ssl.berkeley.eduthe screen saver will sift through radio signals collected by the world's largest telescope, the Arecibo in Puerto Rico, which are transmitted to individual CPUs in the form of "work units." Each work unit consists of a minuscule portion of the signals gathered. "We've built the world's largest supercomputer," says Dan Werthimer, a project scientist with SETI. And he ain't kidding. Since its debut on May 17, SETI users have searched through some 1,198,498 work units, comprising 5445 years of computing time. The lucky user who turns up traces of extraplanetary life will share credit with SETI. So has the search turned up any potential radio waves from distant civilizations? "No," Wertheimer says, "but we're very hopeful that, given another 50 to 100 years of searching, we will." That may sound like a long time, but after all, he points out, "Would you tell Christopher Columbus to delay his voyage for 500 years until he could just fly to America?"