LMS (learning management systems) like Haiku and others - create online classes. www.myhaikuclass.com and https://moodle.org/ and http://www.blackboard.com/Platforms/Learn/Overview.aspx and https://www.edmodo.com/ and http://www.eboard.com/ (although I'm not fond of eboard)
Edmodo is the virtual learning environment (VLE) of choice of several teachers at my school. Its built-in resources and curriculum, class social networking opportunities, grading, and communication tools are hard to beat. This is truly a great resource.
Otus was originally designed to be a service for teachers to distribute assignments, quizzes, polls, reading materials, and essential information from their iPads to their students' iPads. Otus has expanded to support use within a web browser on laptops and Chromebooks.