Accidents happen (lord knows we're had our share), and for some reason they always seem to hit at the worst possible time, normally the farthest possible point from where your car is parked. And that's why we now carry these ultralight first aid kits from Neutron Components.
For such a compact wee kit they pack in a surprising number of first aid supplies - steri-strips, duct tape (also great for fixing bikes), a couple of dressings, and a whole lot more. And perhaps the most useful of all is the included first-aid instruction sheet. Even if you've done a first-response course (which we'd also highly recommend) this sheet makes a great reminder for when the adrenaline hits and everything you remembered from the classroom goes out the door.
Personally we always carry a PLB when out on the trails, but for minor injuries that don't require a heli-vac these first aid kits can make a big difference.