Internet has revolutionized the worlds in many respects. Many educational institutions use the internet to help students with courses, home works, notes, time tables and to watch the lectures again.
There are some individual sites that have collected some of these lectures and have presented them in a single website; and one such website is of the Learners Tv. Http://www.leanerstv.com. Here there are many lectures that have been recorded and uploaded from various Universities. And everything is free.
The subjects offered here are biology, physics, chemistry and medicine. So get online and learn whatever you have wanted to learn from your home and free of cost.