Half the stuff already mention plus a few strong, releasable cable ties.
I actually have those rattling around in the bottom of most of my bags, so I guess that's #11
You might want to consider toilet paper. Not photography related, but some comforts of home can't be beaten!
Good idea, as the Zeiss wipes can be a little small
A basic Silva-type protractor compass is very handy when you're trying to work out timings and angles for the sun when you're shooting outdoors, and it doesn't take up much space.
Good one, though I never get lost - LOL
7. a few Polarizers (B+W)
8. a few ND filters (B+W, Lee and SingRay)
9. a few ND grad filters (Lee)
10. Gerber tool
11. small water-level
12. Datacolor Spyder Cube
I take polarizers with me over 90% of the time, and grads most times. I have a Gerber tool in my car, and take a snake bite and first aid kit me most of the time I'm outdoors. I have lost many of those levels, but fortunately my 5DIII makes them obsolete, except for critical applications. I still have one for my 5DII, though.
Also, do you find yourself using the Spyder Cube much? I've often considered getting one for my studio, but don't know if I would use it enough.