Web Conferencing
Yugma: FREE Web Conferencing, Online Meetings and Web Collaboration
What is that, you say? You were setting up something in-house to do this? Well... that's just silly.
Design based on Modern Art by Jonathan Slenders courtesy of Open Web Design and Web Hosting Geeks
Thinkature also looks nice for whiteboarding and audio conferencing. The desktop sharing part I find a little strange, that seems to serve an entirely different purpose, unless the "meeting" is some kind of tutorial.