9/27/13 Update: Many months ago when I first posted this, I was convinced that my Bianchi Volpe would remain a single speed until the end of time. Yeah, whatever. I need to come to terms with the fact that I change bikes and components like most people change their socks (speaking of... I should probably change my socks more often). My Trek 311 has taken over single speed duties, so this bike is now set up much like it was when I first got it, with a 3 x 8 touring drive train with bar end shifters and 35mm Panaracer Pasela tires. I call it "the Green Monster." With this setup, I use it primarily for rides that involve a lot of unpaved roads and trails. I've lost track of exactly how many miles this bike has on it, but it's now well over 15,000. Long may you run, Green Monster.
I bought the Volpe new back in 2007. I had completely worn out my previous commuting bike (an early 90s Trek Mtn bike) and wanted something a bit sportier, but still tough enough to take the abuse of year-round commuting. The Volpe is sort of a touring bike, and sort of a cyclo cross bike, but probably best suited to being an all-around, go-anywhere, do-anything transportation bike.
The Volpe originally had a touring drive train, with a triple crank and an 8 speed cassette, but after about a year of commuting on the Volpe I decided to convert it to a single speed cuz all the cool kids were doing it. The Volpe's horizontal rear dropouts made the conversion easy and I instantly fell in love with single speed riding. Since then I've put about 10,000 miles on the Volpe. I ride it to work nearly every day and it's often my choice for 200k brevets and permanents.
For me, this bike is like that old worn-in pair of Levis that you hope will never die. It just feels like a part of me when I'm riding it. This bike sees more use by far than any other bike I own. It's been through some minor component changes here and there but it will remain a single speed until its dropouts drop out.
Front wheel: Mavic A319/Shimano DH-3N80 Dynamo Hub
Rear wheel: Mavic Open Sport/Surly Track hub
Crank set: Sugino XD500T w/ 44T chainring
Front D: nope
Rear D: nuh-uh
Shifters: as if
Freewheel: White Industries 18T
Stem: Stock Bianchi
Handlebars: Stock Bianchi
Brakes: Cane Creek Cantilevers
Brake levers: Tektro
Saddle: Selle San Marco Regal
Fenders: Planet Bike hardcore
Tires: Panaracer Pasela 28mm
Headlight: B&M IQ Cyo