For starters, I am going to mention two free, online organizations.
If you know of other organizations that fit in this category, let me know.
This is perhaps the best online learning websites in the world.
If you want acedemic training in a great number of fields, this is a great website to use.
This outranks the next school only because it can help someone start from scratch.
How can MIT be second place? I am not primarily concerned with people who can handle this level of instruction. I am looking to work with folks who haven't had any opportunities and ache to find some.
MIT began offering their old (some of them are less than five years old!) classes, free on the internet!
Check it out if your brain needs some exercise. Some of the best teaching in the world happens there.