Everyone should be carrying extra strings when they play a gig. It's a given. But don't forget to carry an extra bridge pin or two. I recently saw a string break that pulled the bridge pin (which must have been loose) and flung it across the room. The player couldn't find it, so he couldn't replace the string. Bummer. The spare doesn't even have to match - it just has to last long enough to get through the gig. The odds of this happening are pretty phenomenal, sure, but how much room does an extra pin take up?