Ringful's group call service let you start group / conference calls at anytime from anywhere. Instead of requiring people to remember the conference bridge / pass code and dial in at the same time, the service calls attendees and automatically connects them. You can invite more attendees ad hoc as the call progresses.
Best of all, you can group call people from all over the world without paying any long distance charge. If you make a group call from your mobile phone, you will only use air minutes for a single call -- NO multiple legs of air minutes charge!
You can also conference in automated services to do things you can never do before. For instance, conference in Google 411 to help you decide where to eat among a group of friends. Conference in Jajah Babel service to speak to a Chinese speaker on the other end of the phone. You can see all those services from the demo section of the site after you log in.