Music Festivals throughout the summer, not recurring - most of these require purchased tickets:

6/28 - Amesbury, Beer & Music Walk Festival
7/7 - Gloucester, Music at the Museum 
7/12 - Music Town Ipswich 6-10pm - one night only
7/20 - Newburyport, Reggae Fest
8/3 - Manchester-by-the-sea, Festival by the Sea
8/10 - Gloucester, Gloucester Blues [...]