After 17 years in Sag Harbor, Java Nation, a no-frills, small-batch coffee roastery whose owners take their beans very, very seriously, moved to Bridgehampton last year, taking a space in a semi-industrial row of buildings near the train station. A small cafe in front serves up hot cups of Joe, cappuccino, and espresso with a few baked goods and teas to round things out. The big deal here is beans, with devotees willing to drive miles to stock up.