I carry this one:
http://www.avocet.com/tirepages/cross_2_specs.html

Scroll down to the bottom of the page - lightweight folding version comes in 700x32. I might be carrying the 28, not sure.

I've used it a few times, until I could buy another touring tire, then folded it back up and put it back in my bag. It seems fine. Once I loaned it to a guy I met on the road who road over something that ruined his tire. His tire had a 4" ragged-edged gash in it. Would have been tough to boot.