I shadowed an academic peds nephrologist for about 4 years. It was a great experience! I did it pretty much full time during the summer, occassional afternoons, and school breaks. We had clinic three days a week, and I would just sit in on all the visits and go on rounds with him and the residents/med students, and observe the biopsies. The other days were administrative/research/lecture and I would help out around the office, help organize some of his presentations or edit some of his papers/case reports in the works, and go to his lectures. I also sat in on the IRB meetings. I highly recommend it - its great if you can find someone you can establish a long term association with, as well.