Hyannis on the Cape is blessed with not one but TWO places that do great Gelato. The best, in my opinon, is at Caffe Gelato Bertini just off Main Street. It's run by two sisters from Firenze and you'd swear you were on the streets of Florence when you take your first taste.
The other is Colombo's on Main Street. Fewer flavors than Bertini, but still quite good. (and maybe the Cape's best pizza as well!)
Embargo in Hyannis, also on Main Street, does some very nice Spanish style tapas and a pretty authentic paella. Go on a Tuesday night and all tapas is 1/2 price, even peak season. One of the better values on the whole Cape.