I received a suggestion for the Kansas City R Users Group to use screen sharing tools. I am going to experiment with this a bit. Here are two tools worth trying.
Screenleap is a web based system. The person presenting has to download a small software program but others can just joint via their web browser.
Skype has the ability to make conference calls and to share your screen during the conference call.
If I find out more about the pros and cons of these two systems, I will let you know.