Sometimes, we take our Marylandness for granted. Steamed crabs, Natty Boh, Berger's Cookies, and duckpin bowling are just some examples of our unique heritage. And, oh, yes, snowballs, or sno-balls, depending on who's doing the spelling. You can't just drop into, say, Florida or Ohio and expect to see a snowball stand on every corner. But you can here, as surely as the O's play ball and fishing boats ply the Chesapeake in summertime. "That's the attraction," says Bob Ellrich, owner of three Friendly Snowball stands in Baltimore County with his wife, Tanga. "It's a short season.