Speek is a free conference call service that I learned about a few weeks ago on Larry Ferlazzo's blog. When you sign-up for Speek you create a URL for your conference call. Then enter the email addresses of the people that you want to join your call. When the recipient clicks the link and enters his or her phone number, Speek calls them and connects them to you and the rest of the conference. For now Speek only works in the United States and works best with less than ten callers.
Speek - Fast and easy conference calls on the go from Speek on Vimeo.
Applications for Education
Speek could be a good service to use to organize small conference calls for parent-teacher conferences or for small virtual department meetings.