The only first aid item that I carry 100% of the time is After-Bite. I seem to run into fire ants about once a summer, and that stuff is amazing. (Although I *have* gotten myself home with 40 fire ant bites on one foot, it really wasn't fun.) Other than my cell phone and RoadID, I don't have room for anything else. I agree with OakLeaf that anything serious is going to mean a phone call, and from experience I know that I can tough out minor stuff. My normal riding patterns never take me out of cell phone range.

When touring, I carry a purchased first aid kit similar to this, some chemical ice packs, a snakebite kit and some water purification tablets. Since I'll be touring in colder climes this year, I'll probably add one of those reflective blankets.