The MIT Museum is just up the street from MIT and has a nice exhibit on artificial intelligence and robots. There is a pretty cool artsy exhibit with moving sculptures and an awesome exhibit on holograms. I’m not such a big fan of the exhibit on MIT history, though.
They haven’t changed the exhibits in the 1 and 1/2 years I’ve lived down the street, but it was definitely worth visiting again (I’ve been there twice now.) Admission is $5 for the general public, $2 for students, and free for MIT students. MIT students even get to bring in a guest for free. Admission is free for everyone on the third(?) Sunday of the month. They’re closed on Mondays.
Here’s the website: http://web.mit.edu/museum/
Enjoy!