My touring bike has a 6-cog freewheel and 36 spokes/hub. I generally just carry a spoke wrench and figure that if I break only a single (or maybe even two) spokes that I can adjust the tension in the neighboring ones well enough to get to the next town with a bike shop. There are also methods to deal with replacing spokes without removing the freewheel. One is to carry the flexible Kevlar spoke (FiberFix) that you can insert in place of the broken one if that one can be removed; or you can loop it around a spoke on the opposite side of the hub flange if the original spoke can't be removed (see Peter White site for illustration). Another is to carry a spare spoke with the head trimmed down to a 'J' shape that can be inserted in the hub hole - but this requires being able to remove the old spoke and that's not always an option.