Gong is a free system for voice communication on the Web. It allows groups of people such as students and teachers to participate in discussion groups using their computers, using both synchronous (real-time) and asynchronous chat.
That's the official definition from the Gong site. I'm trying it out right now on my Linux box running Firefox and it's not going so well. Gong should run on any computer that has Java installed and while the applets show up OK and appear to function, I've been waiting about 10 minutes for it to "stop" recording after I hit the "stop" button.
I initially thought that Gong was a kind of self-hosted "Leave me an Odeo" type applet but once I fired it up I saw that it was a little more indepth and looks to be as complex as you'd like to make it.
I'm going to try to find some time to play with it a little deeper and see what its true potential is. The website has spectacular documentation and testing pages so if you've got a few minutes to kill, take a look.
Remember how often you've heard podcasters looking for interview recording alternatives to Skype? This might be it.