My brother suggested me nptel.
Its very helpful for engineering students because all the subjects in engineering sullabus are covered in thins sites.
You can choose video lecture notes etc.Classes are taken by IIT profesdors in India. You can do various courses inthe sites and they conduct examination offline and provide certificate which is valid.
Since many are currently using the site it takes some time to losd various links in it .And this is also because its a heavy website with lots of contents in it. Subject wise separate links are privided for easy search of the content and therefore its 90% userfriendly.