Hey guys,
This idea was actually inspired by my good friend and wing, Class. He went to Borders Books and bought a small, thin notebook. He started keeping it with him at all times, and I bought one the next day. He uses it for a number of reasons: Reminders, general thoughts, things he doesn't want to forget, and of course... notes on his own game.
I thought this was a great idea. I've started carrying one of these and a pen everywhere I go. It's about the size of a 3x5 notecard, around 64 pages thick, and fits in the back pocket of your jeans perfectly. I know what you're thinking, and yes, it's small and thin enough that it's no hassle to carry around, and it's still comfortable to sit down on.
The things I use it for are reminders of what I can and should be doing to improve myself. Mostly I use it for my revelations and thoughts on my own game. What I've used it for so far:

Reminders about important things.

Criticisms I've written about my own field reports, and the lessons I can take away from each experience.

My own canned material

Uplifting quotes that I don't want to forget.

Things I try that worked just how I wanted them too.

Things I know I can improve.

Addresses/Phone numbers

And lessons I learn from the world around me.
I keep the book with me all the time because I never know when I'll think of something that I really don't want to forget.
It's like my very own book of cheat sheets made only from my own experiences and thoughts. It helps a lot to read my own field reports because it lets me spot the holes in my game more easily, where I could have succeeded, and where I will succeed next time.
I encourage everyone to get one. It's great. Even if you have nowhere to improve your game, you can still use it as a book for reminders, or more importantly for girls numbers! haha. Give it a shot, I'm sure you'll see benefits and improvements before long.
Always,
~Muse