1. Visit Mount Desert Island’s micro-breweries. In fact, hope it rains all afternoon so that you can do tours and tastings at both Atlantic Brewing in Town Hill and Bar Harbor Brewing in downtown Bar Harbor.  And bring the kids because the tastings include blueberry soda.
2. Buy a book at Port Side bookstore in Bernard.  It's worth the trip just to see the building, constructed in 1891 to store traps and fishing gear.
3. Go antiquing. There are several interesting shops in Bernard, where you can also stop at Port Side and eat at Thurston's. Blue Hill is also terrific if you're willing to drive a bit longer.
4. Shop. One of our favorite spots is The Kimball Shop in Northeast Harbor. Browse among Swan’s Island blankets, hand-painted floor cloths, monogrammed barware, brass doorbells, and Simon Pearce pitchers.
5. Catch up on all of those baby gifts you owe. At Hatched on MDI in Southwest Harbor, you can find many soft and sweet things. They have adorable navy and white striped sweaters decorated with red lobsters.
6. Try your hand at making a blueberry pie. If that’s too intimidating, try a cobbler.
7. If it’s raining on a Monday or Wednesday summer morning, visit the Mount Desert Biological Laboratory in Salisbury Cove. The kids can learn about DNA through MIT-designed LEGO sets and gets hands-on with slimy, prickly, and steely things from the Maine coast. 
8. Check out the matinee schedule of the Acadia Repertory Theatre in the charming village of Somesville. There’s a children’s theatre program in the morning every Wednesday and Saturday during the summer, plus some matinee performances.
9. Visit Southwest Harbor Public Library, a 125-year-old institution that's a hopping place, with storytimes, games, knitting sessions, seminars, and a fireplace that warms the soul on a raw, rainy day.