What-you-see-is-what-you-get (WYSIWYG) seems to be the mantra these days. With video teleconferencing you get it all - voice and picture. Of course, your computer must be set up with the correct hardware to do any of this, but once it is, you can speak to and see other people around the world from your desktop!
CU-SeeMe lets you see and talk to other people running CU-SeeMe. You need a direct high speed connection to do this.
Apple Media Conference
Apple Media Conference also allows you to do this in color and with a shared white board (though you will have to pay for this piece of software...)
Apple does give away a receive-only version that allows you to watch broadcasts of events.