www.timebridge.com- this site allows you to create groups and schedule times to meet. It gives everyone an option to vote for what time works best. I have been using this tool for years for global collaboration and it is simple and easy to use. It integrates with Google Calendar.
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https://www.remind101.com

Here is how I am using Remind101 to connect with students and parents interested in Robotics -
http://robodogs.wikispaces.com/2013-2014+Mandatory+Meeting+and+Summer+Camp+Info

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