There are rare times when New Yorkers are jealous of their suburban bretheren; a Memorial Day weekend marked by barbecues galore may be one of those times. But New Yorker's are a resourceful bunch -- the majority of us may not have yards, but there's always a way to find a grill. Water Taxi Beach is officially open for the season, bringing both barbecue and beach to city-dwellers; soak up the sun, sand, sports (volleyball)......