[Brad]

IRC is the only chat medium I would use for large meetings. It's free and will run on anything (server and client side), if you can't supply your own server you can register a channel on many open servers and large irc networks.

You can tie all this into the forum with a java applet made to work with irc like we use here (there are a few released in the forum). You can also pass along the server details and channel name to your users, your advanced users will like this because they can use an irc client (program on their computer) to connect and chat.

Logging can be done with many of the advanced client programs and/or a bot if you want to get fancy.

IRC requires your users to learn a few commands, but for the newbies a java appelt is enough to get them started as most of them are rather friendly with the buttons and what not .