The low-tech method. Ask people you talk with for their business card. Jot down on the back something to make you remember the conversation, or information on what follow-up is needed. Have a small notepad in case they don't have cards with them.

The high-tech method. Rent the bar-code scanner, made available by the expo management company. Then simply scan your prospect's badge, and all of their contact information is stored. You will probably need a small notepad to jot down follow-up information because the scanner can't tell you what you discussed.