Singlespeed
Surly make single-speed specific frames, the Steamroller and the 1x1. But there's no reason why you shouldn't convert any of the other glorious Surly frames to One-Speedness - the Cross Check and Pugsley both work spectacularly well. A singlespeed crosscheck gives you the option to add gears later, if you ever feel like cycle touring in the Alps, or Cornwall - when you'll be needing all the rack brazeons as well.
