1) I always add a small surgical kit including needle holders, a range of sutures, scalpel blades etc. I used to work in a Vet clinic and have had to use the sutures for cuts and minor stab wounds a few times. A quick suture if you know what you are doing, while the tissue is still largely numb from shock, is much less traumatic than a visit to the emergency room and the 4 or 5 hour wait... more needles and then a quick sewing job that could be done at home. (if you have the skills)
2) I add SILVERLON compression bandage material in sealed packs which is used on burns and to help regeneration of wounds. This is self sterilizing and can be reused many many times. When kept damp it keeps the wound free from bacteria and fungal growth allowing largely scar free regeneration to the tissue. (DO NOT USE SALINE WITH IT THOUGH)
3) I like to have cayenne pepper in a large vial which is useful in case of internal bleeding and it also helps with blood clots in veins and increases restricted blood flow.
4) I always carry either a V-Zap unit or similar spark generator unit to treat venomous bites and stings. I have lost count of the number of times that I have needed them for everything from allergic reaction to mosquito bites to spider and snake bite. Living in Australia this is my absolute must have for my emergency kit.
5) I have a stethoscope, several digital thermometers, a blood pressure meter and at least one pair of bandage scissors.
I have been considering adding some Israeli bandages and an air splint as well...
I keep the entire lot in a backpack that I can grab when I need it. The hardest thing is keeping my youngsters out of it, to them it is a wonderful collection of things. I need to restock my sutures after finding them scattered around the house in an opened state... Grrrr. I guess I will have to get a practice surgical kit and start teaching them emergency suturing