Boston is full of them. When I go into the city to visit my GF I'm always checking them out. Mostly fixed gears for the messengers and scensters and single speed for the rest. I'm also starting to see alot of those downhilll single speeds. Bianchi has couple and so does Trek I believe; Downhill fork, disc brakes, BMX geometry and 26" wheels. Those bikes are crazy. I also made one of my friends bikes into a single speed by simply cutting the chain. I was pretty good so I could just pop the pin back in and bend the chain to work. That's what the single scene looks like in MA.