I am currently looking at oovoo.com as a way of doing it.
We looked at ivisit, but it had problems getting through the firewall...
GoToMeeting is very good, but doesn't give video - that said, sharing your desktop and showing a presentation or showing data, demoing software etc. is possibly more useful. oovoo should also do something similar.
GTM is around $40 a month, oovoo is $8 per user (computer) per month, for a 3-way conference, going up to 8 or 12 way, I think. We have 3 sites we need to link and I have a budget of zero, so it is "challenging", working out a good solution.
Skype is great for 1-1, but can't cope with more than one video connection, going to 3 or more participants is audio only.
GTM goes all the way up to thousands of participants, oovoo is more limited, but for a limited number of attendees, it seems to be a good solution - don't let the personal chat look of the initial website put you off. The free version of oovoo includes advertising, which can be annoying, but the paid versions are ad free.
I specced out a nice little setup with 3 computers, 3 projectors, 3 web cams, 3 conference microphones (with built in noise cancellation and speakers, essentially a USB / Bluetooth version of a normal telephone conference device). But it got dropped down to the cheapest pair of loud speakers I could find and the webcams...
Even the 3 Pentium D computers I tried to spec (I wanted C2D, but knew they would be too expensive) were thrown out, I have to reuse Athlon XP 1.2Ghz machines!
