Bar none, the best ice cream in Maine can be found at Tubby's on Rte 133 in Wayne. Variety of interesting flavors along with the classics.
Everything is homemade with premium ingredients, including the to-die-for hot fudge. They even have a lactose-free selection (quality doesn't quite match the rest, but it's wonderful to have an option for Lactose-intolerant spouses.)
They also have footlong chili dogs and lobster rolls (only surpassed in my experience by Red's Eats in Wiscasset.) It's located near the bridge between Pocasset and Androscoggin Lakes, so there's a very pretty spot with picnic table for sitting and enjoying your food. There's also a dock and spot for public swimming. We often take friends for a summer swim and lunch.
Take it from a Mainer. I know what's good.