[skmurphy]

If folks are waiting in line to talk to you it's fine to say "do you mind if I give you a call or drop you an e-mail to do a follow up" and indicate (politely) that you would like to talk to folks who are waiting. Individuals will sometimes come up after a talk and want to have a 15 minute conversation--or try and have an argument of some sort--when three other people are waiting. It's not being rude to spend 30 seconds to a minute to understand the gist of what they want, make a note of it on their card, and follow up later.