Martha's Vineyard Beaches

Joseph Silvia State Beach - A two-mile beach along Nantucket Sound
Moshup Beach - This beach is by the Gay Head red clay cliffs; it was named one of the Best Walking Beaches in American by the Travel Channel
NESurf.com - This site offers the latest news and announcements about surfing in New England
Vineyard Beaches - A roundup of local beaches from mvy.com

Coastal Trails

Coastal Trails of Massachusetts - Not all of these spots have swimming, but this is a great list of scenic trails along the Massachusetts shore, compiled by the state