Great Artisan Bakery in Cambridge, MA
Another bakery to add to the bakery map . Iggy's Bread of the World is a fantastic bakery, with most of their breads leavened with wild yeast.
Here's their site: http://www.iggysbread.com/main.html 
Address: 130 Fawcett Street, Cambridge, MA, 02138
Iggy's retail store and bakery is a bit hard to find. It's in an old industrial area, but folks seek them out. Most of their business is wholesale, but it's well worth going to the shop to pick up their wares. Raisin pecan is amazing (great for French Toast), their bagels are delightfully old-school (with garlic and poppy seeds all over the bagel, not just on top) and their baguettes are top-notch.
Worth checking out if you're in the area.