I can't say that I remember much of the material I studied during my undergraduate years. I read dozens of contemporary novels and can't recall a single plotline. I memorized pages of Chaucer in Old English, and promptly forgot every word. But, the one thing I did learn is how to learn. A recent article by Jeff Atwood summarizes this skill perfectly:

"The value of education isn't in the specific material you learn-- it's in learning how to learn...Passively reading the material in an encyclopedia or textbook is learning, in a sense. But learning how to research and question the material you read-- and, as in Wikipedia, how to update it so you're adding to the communal wealth of knowledge-- is a far more valuable skill. This kind of participatory, hands-on experience outstrips any kind of traditional classroom textbook. Why read textbooks when you can help write one? There's no substitute for learning on the battlefield. "

Whether you're learning online or in a traditional classroom, knowing how to find and digest complex information is one of the most important skills you can develop. For more on this see: Learning, or, Learning How to Learn.