From NROC:

The National Repository of Online Courses (NROC) is a growing library of high-quality online courses for students and faculty in higher education, high school and Advanced Placement©. This project, supported by The William and Flora Hewlett Foundation, facilitates collaboration among a community of content developers to reach students and teachers worldwide.

Courses in the NROC library are contributed by developers from leading online-learning programs across the country. All courses are assessed to ensure they meet high standards of scholarship, instructional value, and presentational impact. NROC works with developers and contributes resources to improve course quality and to provide ongoing maintenance. NROC courses are designed to cover the breadth and depth of topics based on generally accepted national curricula and can also be customized within a course management system. (read more here)

Link to NROC here