I recently read "On Intelligence" by Jeff Hawkins. The book is about the author's efforts to understand the human brain's mechanism for intelligence and to apply it to machines. He presents a model of intelligence called the memory-prediction framework.
This was perhaps the first time I had read a somewhat detailed analysis of the possible mechanism that drives human intelligence. Some concepts that I found especially interesting were that of invariant and hierarchical memory. Also, the idea that the brain predicts all actions before they are executed was fascinating. If the subject interests you, I highly recommend it. It is quite readable.