From Citrix Systems:
GoToMeeting is a Web conferencing tool that allows you to meet online rather than in a conference room. It's an easy and cost-effective way to organize and attend online meetings. Patented technology enables co-workers, customers and prospects to view any application running on your computer in real time. With the flexibility to meet in person or online, you'll be able to do more and travel less. You can hold as many meetings as you want--no overages or hidden charges. Phone conferencing and VoIP is included.
What's new in this version:
Version 4.0 offers Mac compatibility and VoIP.