Coursera
Link: : https://www.coursera.org/
Recommended for : Amazing Online learning portal for anything and everything especially for STEM and Business Related courses.
Code Academy
Link: : www.codecademy.com/
Recommended for : All kinds of coding
Udacity
Link: : https://www.udacity.com/
Recommended for : Surf there andknow more :P
Mozilla Developers Network
Link: : https://developer.mozilla.org/en-US/
Recommended for : Anything related to web and mobile development, Firefox OS
iTune University
Link:: (Only if you use an apple device) http://www.apple.com/education/ipad/itunes-u/
Recommended for : All the courses from Ivy League Universities, You can do the homeworks and assignments as well
MIT Open Coursewear(OCW)
Link:: http://ocw.mit.edu/index.htm
Recommended for : All the courses taught in MIT
Stanford Online
Link:: http://online.stanford.edu/courses
Recommended for : All the courses taught in Stanford
TreeHouse
Link:: http://teamtreehouse.com/
Recommended for : Web Development
Codeschool
Link: : https://www.codeschool.com/
Recommended for : JavaScript - HTML/CSS - Ruby
Khan Academy
(Podcasts - Mostly for Apple)
Link:: www.khanacademy.org/
Recommended for :Basics of STEM
Microsoft Student
Link:: www.microsoft.com/student/
Recommended for : Getting free licensed softwares, tutorials on all the MS product development.
Microsoft Developers Network
Link:: msdn.microsoft.com
Recommended for : Microsoft development