If you have some, bring Bitbills or physical bitcoins (or both) and a smartphone with the Bitcoin Wallet android client or http://www.webcoin.ch
The sign doesn't hurt, but the physical bitcoins are what show that bitcoin is here, now -- ready for us to try using to try and disintermediate the bank.
I have a few bitbills but not enough to pass out. Just to show. I plan to have business cards and a sign. I will try to bring a table if possible. I'll also have flyers. I'll bring my smart phone too in case someone wants to buy bitcoins via the Mt. Gox app.