For commuting, I don't carry spare spokes, but I do have a multitool with the correct nipple size spoke wrench. Also, any wheel I'm using for commuting -- or even touring -- would have 36 spokes. With regular spoke count and a spoke wrench, a single broken spoke is easily dealt with by truing the wheel still on the bike, loosening tension on the adjoining spokes, allowing me to get home (where there are spokes), or the nearest bikeshop. This isn't the best way to deal with a broken spoke on either a paired spoke design wheel or low spoke count wheel, but who's using either of these wheel styles for commuting or touring? (<-- rhetorical...)

On the touring end of things, I'd have a couple extra spokes tucked somewhere before I stuffed basically unsecured twangy things some place I'd have to listen to them hit the inside tubing over the course of hundreds or thousands of miles...