I have an Adventure Medical Kits "Hunter", one that predates the current "Sportsman" line. To it I have added a mylar blanket, antacid tablets, chewable pepto, eye drops, allergy relief pills, small magnifying glass, decent tweezers, better shears, electrical tape, hand sanitizer (not a replacement for soap and clean water, but faster and better than nothing), lost tooth filling and loose cap repair, alcohol swabs, triangular bandage, extra safety pins, extra roller gauze, combat gauze, QuikClot sponges, wound seal powder, butterfly type wound closures, and extra pads/sponges/bandages of assorted sizes. I tried to fit in a sledge hammer for anesthesia, but it wouldn't fit...
On a side note, at least once a year I go through it and replace any out of date meds, etc. or scummy looking material. The most important thing to do is to be familiar with and practice with the materials you have in your kit. Practice wrapping a wound, putting on a sling or splint on yourself and others, etc. Before each trip I look through my kit just to stay sharp on its location and contents. Familiarity, knowledge, and capability are the three most overlooked necessities in a first aid kit or situation. Taking a cpr / fist aid class if you haven't ever done so can be very enlightening.
