One of the things that seemed to be everywhere was QR Codes (Quick Response). These are a square bar code that appear as follows:
These codes are read by various camera phones (such as the iphone) and will take you to a URL. The above code will take you to this site. I think you should make liberal use of QR Codes on marketing materials - heck I even saw someone with a T-shirt with a QR code on it - and lots of people "snapping" a shot of it to see what they will get. To generate one you can use this link.