I used to carry a small Moleskine notebook, but usually just to record thoughts that might be related to photography, and sometimes indirectly related (inspirations, etc.).
I also have the thinner 3-pack ones that Drew mentioned. Those are actually VERY convenient, and still my favorite.
But has anyone here heard of Piccadilly notebooks? I picked one up a couple months ago, and I honestly can't tell a difference between these and Moleskines...except the price.
http://www.piccadillyinc.com/products_notebooks.php
Edit: Oh geesh, I started this post just before I left the house, and didn't finish it. Now I see Christopher beat me to it! 😱