The Vilano Urbana that Delia mentioned above appears to be an aluminum frame clone of the Dahon Speed Uno, which is Dahon's fancier version of the Boardwalk S1. Since they're single speed, they'll have a rear hub spacing of 110mm.

rhenning appears to have 2 Boardwalk D7's which probably have rear hub spacing of 130mm, but are usually 2X+ the price the S1 (unless you can get the same deal as rhenning).

Nexus 3 with coaster brake is 120mm, or 127mm-135mm with their other brake options.

A long time ago, I bought the S1 for the chromoly frame and horizontal dropouts, but I didn't put in a Nexus 3...