jbonifer has a good list, I could do without the wipes, iodine and neosporin till I got back to camp though. I also carry vet wrap, it helps hold gauze in place and can hold splints in place if you need it.

From my experience a major threat to hikers/hunters or anyone walking around camp areas and which is often overlooked is the threat of exposure to cold, a must in any pack has to be an emergency blanket (the one that looks like aluminum foil developed by NASA).

Even in the summer season if you are injured and unable to return to camp and are waiting rescuing, the night temps can drop below enough for you to be at risk for hyperthermia.

Also, camping matches, lighter or the best device is the magnesium stone is must to start a fire. Fire has been providing physiological comfort to those either lost or waiting for rescue as well as an obvious heat source.

I would also consider carrying a whistle and a small length of cord and a backup compass just in case…

Matches compass water fire starter and flares

In addition to the above in my pack I carry a small bottle of Vaseline and it has more uses than anything else you can carry. Being a former Search and Rescue member, keeping your wound clean, moist and covered is what you want. Once you get out you can get the additional care you need. One of the best uses for Vaseline and a magnesium fire starter stick is the best way for starting a fire under the most extreme conditions, been dar and dun dat!” Take a 2x2 inch piece of cloth that can also be used as a bandage and saturate it with Vaseline and scrape a little “magnesium on it and hit it with the flint side and now you have instant fire 6 to 10 minutes of flame. I still got the same Vaseline jar in my back pack some 10 years ago and still work as good as the day I put it in.

OK FIRST AID NOT SURVIVAL KIT

2 rules of thought on this
Altoid size can or 6x9 dayplanner size.
Altoid first, Asprin, triple antibiotic, 2x3 bandages, bandaids, tweezers and a needle.
for a dayplanner size go on EBay and search it.
you can get a 200 piece set with anything you want.
THAT'S ONLY FIRST AID
For a survial kit your up to fanny pack size, and should think about food, shelter, fire and living for about 3 days. you can and will use stuff from your first aid kit for survival. Clay had a post about using your vasaline for a fire starter that I had never thought of, and you could always fish with a needle but I would add fish hooks.
I also have some items that I just use for camp such as immodium, chapstick, sunscreen, more asprin, and all of my gause and tape because it won't go in a small kit. when I hunt I usually never get over 4 hours away from the truck or camp so you can wait to actually clean and dress that wound till you get back. That's just me and I'm a little paranoid when it comes to that, I have bought everyone in my family a vehicle first aid kit and keep them stocked at deer camp. NOTHING makes for a more miserable trip than diareha for about 3-4 days.

I like tweezers but that is because I hunt in cactus country quite a bit.

Also doesn't hurt to put a few bandades for small cuts to limit the chance of infection.

I carry Adventure Medicals little pocket doctor in the waterproof bag it comes in. I added some alchahol pads, bandages, and some TP. I held the kit underwater, and under my faucet on full blast, and not a drop of water got in. The kit cost me about 8 bucks!

I reccomend some hooks, line, matches coated in wax, match strike paper, compass, and water purifier.
all packed in plastic waterproof bag.

This is more a question than an answer. There were no mention of any antihistamine for the 1st aid kit (perhaps, I missed it). I have no experience with survival, but to me it make sense to have one. You never know what you may have, or develop an allergy for. And this thing can make a big difference before you get back to the camp and does not take much space. Just my opinion. Have anyone experienced a need for it?

neosporin, bandaids, gauze and scissors.

the most important thing you can have in your first aid bag is knowledge. You can do alot of things with nothing, but the stuff around you. Spint broken bones, cover wounds, and stabilize injuries with the woods you are in. Knowledge is power.

Absolute necessity: Gauze and Tape - you can fabricate just about any size temporary bandage with that. Some triple antibiotic is also high on the list. Sticks can function as temp. splits with the tape.

Duct tape. It will serve many purposes.

Three things i have in every aid pack i take with me hunting,fishing or even while i've been deployed overseas. Superglue or liquid skin for small cuts, hydrogen peroxide gel,and mole skin for blisters. Of course you always want to have tape and gauze. Quick clot is realy cool stuff but it has an expiration date. I'd recomend israli bandage (its a realy cool ace bandage with gauze atached) and somthing to make a toriquite with. Im no doctor so i hope this helped ya.

For immediate life threatening injuries (that you can fix on your self) you will have to stop bleeding so if you can get your hands on some 4x4's and that would be great. The would should be cleaned, sterile water is used in the hospital to irrigate wounds, this will reduce risk of infection. If you are impaled by something (ie branch, arrow etc, DO NOT REMOVE IT, bandage around to hold in place and get to and ER. The object may be next to a blood vessel and removing would cause excessive bleeding. Knowing CPR and first is beneficial to any outdoors man. Being a paramedic I suggest taking a formal class but these are two instances that I could think of where having water and bandages can make a difference outcome.

A lot of what you need is dependent on just where you go in the pursuit of your outdoor experience. How far are you from emergency help? Basic stuff like rolled gauze, ace bandage, gauze pads, duct tape, etc. are all needed. I noticed that someone above indicated a concern about Quikclot having an expiration date.
I have had some experience with Quikclot and simply would not go into the outdoors without it. A small cut can turn into a tragedy if you are far from help. 4 x 4's and pressure can deal with a number of issues, but a bleed that can't be controlled can be life-threatening. My experience was with a friend on a hike who fell and gashed his leg. I believe that, if I didn't have Quikclot, he could have lost his leg or even died. I was able to put several Quikclot Sport pads on the wound and applied pressure for several minutes and the bleeding stopped. I had already tried using conventional gauze pads and holding pressure for quite some time to no avail. The Quikclot gauze has something in it that causes the blood to clot. It worked perfectly with the situation we were in.

On other occasions in the Canadian bush, I have seen really severe injuries that required extraordinary measures to handle including an ax wound through a guy's foot. Quikclot would have made those issues less of problem.

I strongly suggest that you include several Quikclot packages in your kit. It is very light, compact and could save a life.

there are a lot of good answers up there, as an EMT use your head, get a first aid refrance book, READ IT, then make your kit, i would include duct tape due to its water proofness, but a lot of the kits that you can buy are good kits just know that if your going alone use your head.