Another must have is a whistle- something like a fox40 - lot easier to blow a whistle than yell if your stuck- anyone seen movie 127 hrs?
For first aid kits I have a couple different small ones- Company called Adventure Medical makes some small personal kits for 1-4 people for 1-4 days with all kids of options. MEC in canada or REI in US are 2 places I know for sure have them.
shown below is the .5, 1 person 1-2 days with macro 100 mug and EW-83H for reference


I'm planning to get back into hiking this summer so would love to hear more feedback, or other options people are using for back packs.

I used a seperate bag last year for gear and personal items- and that just didn't work for me.