Neat video of LMC / Von Neumann Architecture / Sharing site
http://www.youtube.com/watch?v=FtW9rtmPBU0
I've found it helpful since I've started learning assembly to understand exactly what I'm doing with the stack and the registers and so on. I knew some of the basics, but seeing this has helped clear it up for me. This is more of the theory and operation.
http://www.youtube.com/watch?v=WIDzNyfVVg0
This one actually explains in detail. I've taken a lot of physics and engineering classes, but never really understood how it's working without any abstraction. It explains NOR, NAND, XOR, as well as the simpler AND, NOT and OR.
This is totally unrelated to the other two links. I didn't want to make a separate thread, though. This is a sharing site. I've found very interesting books here (they even have most of my college textbooks). For example, you can find anything from the Trachtenberg Math System to complex engineering and fluid dynamics design programs.