Wiggio is a free site that allows you to work with groups online. You can create a group for your class, for your team of educators, or even your whole school. The site allows you to have shared calendars, send email, text and voice messages, create to-do lists and assign tasks, create polls, upload and share files, and host virtual meetings and conference calls.
This would be great for teachers and schools to use for class and group work and collaboration.
There is also an iPhone app.