Wow. This brings back quite a few memories. A number of years ago (15 to be exact), I spent a good portion of my final semester senior year at MIT in a lab (6.115) programming the 8051 in assembler and wiring interesting things up to my nerd kit. Taught me a lot about how computers work at a low level and interact with other devices (I remember using an oscilloscope to watch bytes coming in from a MIDI device that I had wired up to it).

Going to the course website, it looks like they still use the 8051, and the same professor is teaching the course.