The Corner Bar is a hangout with a fine hamburger, cold beer, and a seat by the window, where you can watch Sag Harbor go by. Beer on tap may be a better idea than the inexpensive wines by the glass. You might be surprised by the menu. Sure, it has nachos and fish and chips, hearty fried chicken and some quesadillas, but it also has some dishes for the Harbor's health-food crowd, such as beet and spinach salads. The noise rises to a crescendo as the evening progresses.