Microsoft Live Meeting:

Live Meeting is a web conferencing service that allows you to collaborate with team members, view and edit the same document in real-time, and share presentations without traveling or reserving a conference room.

As a Live Meeting Organizer, you can schedule and conduct online meetings with remote participants – without ever leaving your desktop.

For Presenters:
https://www.livemeeting.com/cc/usergroups/loginPage

Downloads:
http://office.microsoft.com/en-us/downloads/CD102549901033.aspx