I've got a Jamis Nova, and it's a great steel all-rounder. Not sure if they just sell the frameset, but it's worth looking into. As of 2008, what used to be the Jamis Nova is now sold, with some modifications, as the Jamis Aurora Elite.

You could also consider Steelwool. Their Tweed is a really nice-looking frameset — I like the eccentric bottom bracket.