Never use one word answers. If someone asks you what you do, explain to them a little bit about it and some things that are interesting about it that they can pick up on and ask you questions back about.
If you just answer that you're an accountant (or whatever you do), there's not really anywhere to go from that, especially if the other person doesn't really know anything about accounting.
Also, other people should be doing the same. Listen for little bits of info that they drop. If they are dropping info, they probably are willing to talk about it.
There is a good book called "How to talk to anyone", I know your conference is probably today (maybe tomorrow) but if you've got a chance, you could take a gander at this book.
http://www.amazon.ca/How-Talk-Anyone.../dp/007141858X