I just wanted to add another round of kudos for Tacos Lupita, the Somerville taco spot. It is the ultimate Chowhound find. Unassuming, out-of-the-way, un-trendy, but with amazing, fresh food, nice people, etc. I am a regular take-out customer there, and I just want to say that their pork tacos are the BEST (chicken is also good). They roast the pork on a spit and then shave thin slices for the tacos, so there are all kinds of nice crisp pieces of the pork. (Don't bother with the burritos -- the tacos are what they do best.) Be sure to get their special hot sauces with it, on the side.
Last time I was there, I watched as they made their tortillas by hand, from the dough, to a tortilla mold, to the frying pan. We typically don't eat in the restaurant -- it has zero ambience.
I'm a Californian, taco aficionado, frequent Mexico traveler, and I can tell you, these tacos ROCK.