Google+ Hangouts
Hangouts provide an excellent video conference facility for up to ten people simultaneously. Sound will automatically cut to the person currently speaking, temporarily muting background noise from the other participants. Simply click on any of your contacts in Google+ and select Invite to Hangout.
For more information see the Google resources below and don't forget to checkout hangouts with extras which allows you to collaborate on a Google Doc, Spreadsheet or Presentation within a Google Hangout video conference.