Freecycle. Get bicycles, furniture, computers. All for free. www.freecycle.org.

Museums. Museum of Fine Arts (MFA), free on Wednesdays (except special exhibits), Institute of Contemporary Arts (ICA) free on Thursday evenings 5pm-9pm.

Haymarket. Ridiculously cheap fruits, veggies and international cheeses (1/2 price or less), all in an old-world open air market. Fri Sat 6am-6pm.

July 4th Fireworks. At the esplanade/hatch shell on the Charles River.

Movies/DVDs. Boston or Cambridge Public Libraries. Rent for free once you become a member. Seriously. No NetFLIX or Blockbuster. Selections are bit more limited when it comes to the latest movies, but the variety of movies is usually much wider than your local movie rental store.

Beach. Take the red line T to Andrew Square, walk 8 minutes to the beach. Or take the blue line T to  Wonderland or Revere Beach.

Boston Public Gardens. Gorgeous in the summer or the winter. Not as big or varied as Regent's Park in London, but picture-perfect enough. Other beautiful parks and botanical gardens are part of the huge Emerald Necklace chain designed by Frederick Law Olmsted.

Lectures and events at MIT. See MIT's events calendar; many events through the year, many of them free and open to the public. Unlike Harvard, MIT is a much more of an open campus.

Free concerts. Some free concerts/music events in the area: Honk! (in October) and the Cambridge Carnival (in August or September).