I forget if it was at Boca or Miami, but somewhere along the way, there was the story of the one girl who wanted to be a vascular surgeon, which apparently is a pretty hard residency to match into. The administration had hooked her up with a practicing vascular specialist, and by the time she had graduated, she had scrubbed in (maybe even assissted, can't remember) on over a 100 procedures. There was also the one student who was interested in organ transplant, and got to fly out overnight with the specialist, harvest organs, and return the next day to implant. I volunteer in a specialty clinic at school now, and I've had the chance to see several fourth years come in to see the facilities, and I would assume, interview at some point. While your "shadowing time" wouldn't count for much, you would probably have a lot to talk about and/or be pretty knowledgeable about the field having observed a 100 procedures, etc. Also, the way I see it, if you're interested in specialty X, and you've been associated with a practicing physician in this field for several years, they believe you to be pretty competent, and want to see you succeed, they may be willing to recommend you or write you a pretty good letter. Of course, letters from your rotation directors, grades, Step scores, etc., would still be paramount, but at the very least, its not going to hurt you.
