Chairman's judges really appreciate a well-prepared document supporting your presentation. I'm sure there are many RCA-winning teams with excellent examples they are willing to share.
News clippings, thank you letters, event photos... hard evidence to support your claims of awesomeness are what I tend to look for first.
It doesn't have to be a binder... a well-organized folder or display board could do the job just as well... what matters is that it has useful information in support of your presentation and written submission.
And while you'll find plenty of judges coming by your pit area, there is a good chance that they are not the RCA judges. The RCA judges would love to get down to the pits, but in my experience RCA judges have their hands full with presentations and feedback forms... not to mention the task of figuring out the most deserving team. Dang you guys make it hard sometimes!
Of course the judges all have lunch together and share information, so it never hurts to put your "best foot forward".
Jason