The Big Dummy was Surly's answer to Xtracyles' open-source design of their product.. Surly built it to take the Freeradical frame and Freeloader panniers, did a great job too.
Check out El Cargonista's Flickr Pictures of his big Dummy "The Goat" it's a work of Goat loving art!
I built up the Xtracycle myself from an old Schwinn mountain bike frame. It has it's idiosyncrasies (notably the rider ) but it's great for hauling.
I've got most of the kit loaded on it now (I cheated, cut a hole in the bottom of my tent bag and stuffed the whole kit and caboodle into it like an oversize Bishop. not tight nor pretty, but it will get me out this afternoon) now to dress warm, grab some food and head out!
Jerry, why oh why did you sell the X? and yes I'm a Grant Peterson fan having an XO-1 and a Waterford Heron Touring in the stable too!
Time to ride.