The Highland Street Foundation (highlandstreet.org) sponsors free admission to a variety of museums and cultural attractions on Fridays in July and August. No tickets are necessary, just show up (but don’t be surprised if its crowded, a lot of people like the free admission).
The formatting messed up as I tried to paste it in, click on the link to get to the schedule.
http://www.highlandstreet.org/index.php?option=com_content&view=article&id=79

Click here to download and print the 2011 Free Fun Fridays Calendar
*Free Fun Fridays 2011 Special Instructions
Shakespeare on the Common (July 29, 2011)
This is an open-air, evening (8 pm) performance on the Boston Common, with no seating structure. This year the Commonwealth Shakespeare Company presents the comedy All’s Well That Ends Well—Shakespeare’s globe-trotting adventure story of how far one woman will go to win the heart of her beloved.
Tanglewood (August 12, 2011)
This is an open-air evening performance on the Tanglewood grounds (located in Berkshire County of western Massachusetts, just a short drive from the Massachusetts State Turnpike). All lawn tickets are free (14,000 capacity). A prelude concert starts at 6 pm, followed by the Boston Symphony Orchestra at 8:30 pm.
Boston Harbor Islands (August 19, 2011)
This is a free ferry ride to either (or both) of the two most popular Boston Harbor Islands – Georges Island (with historic Fort Warren and ranger-guided tours) and Spectacle Island (with a life-guard supervised beach and 5 miles of hiking trails).
Free tickets for the Harbor Islands Express Ferry will be distributed first come, first served at Long Wharf-North in downtown Boston (near the Aquarium subway station), with lines forming at 6:30 am. The ferry leaves every 30 minutes starting at 8:30 am, with a 3 hour window to return. Each person in line may pick up a maximum of 4 tickets. (There will be no special arrangements for groups of more than 4 to be on the same ferry.) Tickets will be handed out for the earliest ferry, then the next, and so on, until all ferry seats for the day are distributed – last year, all tickets were distributed by 10:30 am.
New Repertory Theater (August 26, 2011)
This is an evening (6 pm) performance of The Adventures of Huckleberry Finn in the Charles Mosesian Theater in the Arsenal Center for the Arts in Watertown. This venue has a 340-seat capacity – no reservations accepted.
