E-Learning web sites
Coursera
I think it's the most well known e-learning web site.
What I studied here : Scala, Crypto, algorithms, Big Data, Gamification, processing, startup engineering...
Web Site
Udacity
Many online courses.
Web Site
edX
Another one, with many subjects.
Web Site
KhanAcademy
Really good resource to check and improve your math basics, from simple additions to calculus.
Some other science and programming topics but not as good as maths.
Web Site