We've been playing with a new tool, Gabbly, as a possible means to run live chat on the NetSquared site during the conference. Gabbly lets you add a chat window to any web page on the Internet, simply by typing "http://www.gabbly.com" in front of any URL. For example, you could chat with other folks reading the NetSquared blog by typing in the URL "http://www.gabbly.com/netsquared.org/blog" — check it out!
Gabbly keeps the last 18 messages in the chat room visible to anyone joining the room; and as long as you keep the chat windown open, you'll see ALL the messages typed since you logged in (plus the up-to-18 that were then when you arrived). And since Gabbly generates an RSS feed for each chat room, you can archive the chat about any web page by aggregating it back onto that page (as long as your web site has a built-in tool for aggregating RSS feeds).