Trying to count the islands off the Maine  coast on a map is a sure way to get a headache. Hundreds of spits in the ocean trail off the rock fingers of the coast. Many of them, of course, are little more than perches for tired seabirds. In the sheltered arms of Penobscot Bay , however, several larger islands have actually sprouted civilization, home to both hardy fishermen and wealthy summer folk. Like the mainland villages, each has its own personality, from the fishing island of Vinalhaven  and the summer resort of Islesboro  to the artists colony on Monhegan .