Since that time, David has continued to add onto the site and I was particularly interested to see that he has similar resources for Real Time Conferencing, also known as "web conferencing".
Using these tools, people can participate in a conference call and view a presentation on their computer screen at the same time. The presentation on their screen is controlled remotely- all they need to do is watch.
In addition to the tools, he also links to a number of reviews:
I've used web conferencing (via Webex) every week for the past couple of years and I believe we'll see more solid growth in using these tools. They'll never replace the effectiveness of face-to-face training/meetings, but they can certainly be a cheaper alternative to expensive traveling. I believe web conferencing works.