Ever wanted to take extra classes in your spare time? Yah, me neither. Except I stumbled across this site which offers free, that's right, free courses. You can pay a little money to get a formal certificates for some of the courses which are available in any subject - programming, math, science, etc. Best part is that the courses are offered by accredited universities around the world like Harvard, Yale, USF to name a few. So if you're currently in uni, maybe you can even get credit!

Check it out at Coursera