Getting around Boston
Boston public transport is actually pretty good. Subway (called the “T”), and especially the red line serving also Harvard Square, is reliable. Make sure to get a plastic Charlie card (it is free, ask a subway service person for it), since the paper ones are more expensive per ride because of an ecological surcharge.
Getting to/from the airport: by public transport, the easiest way from the airport is to get a “Silver Line” bus (on subway maps reflected as if it was a train, but it isn’t) to South Station and a red line from there. The ride from the airport is FREE! If public transport is too public for you, and yet you find a cab too private, SuperShuttle, as well as Go Airport Shuttle offer shared ride shuttles to/from the airport.
Lyft offers a really good alternative to taxis (private car owners offer rides), allegedly it is also less privacy invasive and more driver respectful than Uber, although the latter is more popular and has many cars in most cities. And remember you can also bike!
Harvard shuttle: for safety reasons, Harvard offers a 7pm-120:30am shuttle, which can pick you up and get you to another location within Cambridge for free (there is even an iPhone app to track the shuttle!).