SOMERVILLE - On a recent Saturday morning, five twentysomethings huddle in a cozy living room to map out their day. Two are from Montreal. Another is from Chicago. The hosts, Jesse Fenton and Erin Benoit, have lived in the apartment for three years. The guests have had plans to visit for more than a month, but their only contact with their hosts has been through computer screens. The five met through CouchSurfing.com, an online network of travelers mostly in their 20s, who are tired of staying in hostels and hostels and who want to see the world with a free place to crash - often on someone's couch. But what sets CouchSurfing.com apart from a bevy of similar free services such as hospitalityclub.org is its focus on its mission, which according to the groups website "is not just about free accommodations" but about human interaction. "It makes the world a smaller place; says Benoit, 25, a medical technologist : at Boston Medical Center. "Eventually; we'll have friends all over the world. Host offer the use of their couches, bathrooms, kitchens, and spare beds. They sometimes provide meals and even the use of their cars. They give their guests tips about local attractions and often show them around. [ ... ]. Tesse Fenton's brother Casey, a New Hampshire resident [ ... ], hatched' the idea for the website after planning a last-minute weekend trip to Iceland. Instead of booking a hotel, he e-mailed 1,500 Icelanders through the University of Iceland student directory, looking for a place to stay. Within days, he received more than 50 responses offering free digs. "When I was leaving there after the long weekend, I said to myself, 'This is how it should be every time 1 travel," he says. [ ... ] Vincent Fugere, a 23-year-old graduate student from McGill University in Montreal [ ... ], says CouchSurfing has changed his perception of the United States. "Americans aren't as bad as the press makes them out to be; Fugere said jokingly. "I thought aIl Americans carried guns –