for planning and running virtual and real meetings--from Anjali Sastry

My 990 students converted me to this service for conference calling and international calling--all you need is a headphone with a microphone.
It's free!
And you can IM using it too.
http://www.skype.com

...

And to invite people to a meetings, consider using http://diarised.com/ --from Kara Penn

Make sure to look at the ideas posted in the pages on effective meetings.