I had been using a Park Tools Rescue Tool MTB-3 (had two of these - wore out the first one) but my current favourite is a Serfas ST-LV Multi Mini Tool. Never heard of Serfas before but it's a great (not so) little tool for a longer tour (and apparently no longer available anywhere).
Last edited by porter; 05-08-10 at 10:15 PM.
Reason: Additional info added