What computer science learning resources do you know about?

I want to find a resource (or collection of resources) that covers finite areas of CS that I can dip in and out of whenever I am bored or have free time.

e.g.

I have some free time today, I visit resource X and learn about Artificial Intelligence. Tomorrow I have some free time, I go learn about Computer Vision. Next week it's Mobile Telecommunications or computer hardware or information management.

I am not really looking for a continuous college course - I already have a CS degree.

What resources do you use?