I use a pen when I read. I underline important bits and actually write down the key points in the margin. Writing these things down helps memory and I don't really care about leaving the pages in the same state that I found them. Also I don't always have a notebook with me, and I do this to my own books only. I just don't care about "ruining" a book -- I want the knowledge!

Of course you might not want to borrow some of my books when I leave them in this state -- they look like study aids from a med school study-a-thon. But whatever trick YOU find that helps you pound knowledge into your brain is worth it.

Mr Polad, my 8th grade US history teacher taught me this same lesson. It does seem tedium at first, but I've never found anything better at retention.

Granted I think taking a lecture on the same topics is a major reinforcement.