Are you ready? With Memorial Day weekend now in the books, you kind of need to be. Summer now. And here in Duluth and in the Northland that means busy-busy, our time to shine, to play, and to cash in before the next year's deep freeze roars its return. It's weekend after jam-packed weekend, get there, do that, do more. With an abundance of attractions and summer events, Duluth welcomes more than 6½ million visitors every year, a majority of them…