OpenProjects is a free IRC network dedicated to technology. What I liked about them was that they don't allow Porn or Warez, so all the channels are technology related. Just open any IRC client (like mIRC) and use "irc.openprojects.net" for the server name and then any nick for your name and you're in.
The only cost comes in providing a web based chat client.
JPilot is probably the most popular and runs $50 bucks. There's even a hack that will tie it into vB [
link].
If you're not that familiar with IRC, I'd be more than happy to set everything up for you. And give me a few minutes and I'll have a working copy running on my new board, so you can see what it looks like.