In today's live no matter where we are located, we can connect anonymous people around the world simply by clicking a button inside our PCs. we often not only meet each others but also share our businesses, our thoughts and our educations. most of people some times hate to go to courses and pay big monies for what they learn. most of this courses are even for trad. they collect our money and deliver a basic of a program. in my opinion, the real people are in virtual world. They are wasting their time to teach and share what they have learned and experienced along years and they offer their educational services for free.

There are lots of websites offering online learning service but i am interested in top 5 of them as below:

1. MIT Online University
The MIT Online Portal of learning offers many topics with sub categories on the level of undergraduate and graduates. You can find your favorite courses in your wanted language as well. all courses are open and no registeration is needed.

2. Coursera
 coursera.org is another online portal of learning. It provides many wanted programs and courses for registered users. all you need to register with your open ID and enroll to your course and enjoy the learning.

3. alison
http://alison.com/ is offering two way learning, one is completely free and the others which is only for some programs is certified. for courses you want to get certified must pay a small amount. but most of other courses are free of charge. currently 3 million learners are learning through this site.

4. Standford Online
Stanford online university offers variety of programs with the help of professors from famous universities. in standford online you join the real online class and do assignments, participate in discussions, connect online with your professor and many other features. 

5. Khan Academy
The founder of Khan Academy is Salman Khan an Indian educator. It provide free world first classes for any one in any where.

Note: the above listed are according to my research and experience with. you may have a better address for online learning. please share it in comments.