I was a regular at Hunt's for buying film and processing, both their Kenmore and Harvard locations. They've got a small selection of interesting used and studio gear, too, but I'm told their Melrose store is the big'un. They're all pretty great in there, very knowledgable (as camera-only store staff have to be these days); mostly students and working photographers.
I used to buy online from Calumet until I found out they had a store in Cambridge. Just after I moved back west they opened a much bigger outlet down the street. They specialize in more pro photo/video gear and had a huge selection of studio equipment, not to mention used pro bodies and lenses. I only bought a shoulder bag there, unfortunately. Very knowledgeable staff. (note that when I say 'huge,' I mean huge for a B&M. I always prefer buying in person, even with chains, because I'm antsy to get it in my hot hands, and can test it out on the spot or when I get home and save myself a week transit time sending it back)
There's also a place on Bromfield street downtown that's a tiny hole in the wall, but unlike some of the 'camera stores' downtown that sell mostly phone cards and headphones, they're a real shop. Really odd place, tiny and packed to the gills with a mix of consumer DSLRs and older collectable cameras. Only ever went in there for film.
Happy shopping!