I ran across this pretty cool web conferencing tool called DimDim. They offer a free version that allows up to 20 attendees, and paid versions that allow for up to 1000. They even offer the open source edition that you can download and run on your own server. I tried to sign-up for an account, but for some reason the sign-up page would error out so I have not used the tool yet.
Check out the tool and post back your comments on how you like it. Hopefully, I’ll get signed up pretty soon so I can check it out.
UPDATE.
I got signed up for the service successfully. If you have a need for web conferencing, I highly recommend you take a look at DimDim. One of the nice things about their service is that it does not require any downloads or plug-ins to attend or host a conference. You only need a plugin for more advanced features such as sharing the desktop.