Top 5 learning pages?

What are the top five educational websites that you know of, for any topic or pursuit?

What websites do you learn the most from?

You can also include your favorite news websites, or generally informative and thoughtful spots online. And just if you were wondering; yes, you can include fluther, but give me four other options too.

I really want to learn as much as I can, in general (about the world, about everything.) So if you can recommend something, answer this.

Looking for hubs of knowledge, to be exposed to.