Khan Academy-

Math Lessons and Skills Practice

Udemy-

Free and cheap online courses, also the ability to build your own online course

Udacity-

Free online classes with certifications available after completion

MITx-

 MIT is offering some of its classes online for free

Edx-

MIT and Harvard have partnered together to offer free courses

Coursera-

Free online classes from 16 universities (These are full classes with instructors and students are expected to interact)

P2PU-

Students work together to learn a particular topic by completing tasks

Open Course Ware MIT-

MIT’s course materials online

Code Acadmey-

Learning to write computer code

Open Course Ware Consortium-

Collaboration of educational institutions sharing their course materials

Matterhorn-

Educational and audio content, download and upload teaching videos