Concept art is pretty cool. Not only is it a window into some weird new world, it's a window into someone else's mind, their thinking process; how they see as revealed by what they're showing you.
The same ideas can be extended to any creative process. Draft scripts, novel outlines, compositional doodles—they're all neat little windows into the process, all the more revealing for the polish they lack.
In the world of RPGs, the same could go for rules or published adventures, but the real expression of the practice is in what goes with the GM and the players to the table. What you use as cheat-sheets to either kill a monster or kill with a monster. Since so many different arts and skills converge at that table, I'm willing to bet that every has, consciously or not, developed their own toolbox of information-coding. Whole statblocks or just HD? Page numbers? Doodles or descriptions? How to do you tell yourself what you need to know? I'm curious.
So here's my notes for the last thing I ran. Post your own!