Kind of along these lines...when I first started shadowing, I kept a journal. My adviser recommended this, and I'm really glad that I followed her advice. Every time I came home from shadowing, I got my journal out and just jotted down anything especially interesting that I learned that day, or any event that really stuck out in my mind (a sad euth, a cool surgery, etc). I also put the number of hours that I spent in the clinic down at the bottom corner of the page, so that I could easily go through at the end of the summer and tally them up.
I'd really recommend it. It really helped me write my personal statement.