I just re-read this thread 2x now and figured I'd throw in a few items that have not yet been mentioned but are (to me) common sense. These are more emergency/survivor type of items/tools.
1. First Aid kit- depending on the remoteness of the area you'll be hiking will determine the size and supplies in the kit. Even if I'm only a couple miles out of town hiking, hunting, etc. I have at least a basic kit in my pack.
2. 550 Paracord: Restring your shoes/boots with it. A 100' length of it stows nicely in your pack. You can even use it for drawstrings in a jacket/hoodie or weave it and make lashings and straps for your pack. As a matter of fact, I'm working on some lashing straps for my pack now.
3. A good multi-tool such as my Leatherman Wave. At the very least a good quality fixed blade knife.... or both.
4. Items to make fire (emergency): magnesium striker, old perscription bottle stuffed with cotton balls and a few (5 max) waterproof matches... glue a small piece of fine/medium grit sandpaper to the inside
of the bottle cap. This keeps it from wearing down as it would if you glued it to the outside of the bottle. Also if it's on the outside of the bottle it could tear up any other gear/material it comes in contact with... like a ziplock bag meant to keep your gear dry... ask me how I know.
...I know I'm forgetting a few items and I'll post up once I check through my pack again. I'm a big fan of hammocks as well but that's already been posted. As stated previously, it's not an exact science and only you will be able to determine what works best for you.
Octoberish, I want to hike through the NJ Pine Barrens for a couple days. Ain't scared of the Jersey Devil (lol). Then my next big plan is to start the AT with my brothers and cousins next year when I turn 35.... that's the plan.....