I'm not sure how far you're willing to drive, but I volunteered in the ER at Pomona Valley Hospital and shadowed at their Family Health Center. Two of my classmates in the Scripps College Post-Baccalaureate Premedical Program drove from Claremont each week to shadow a pediatric surgeon at Loma Linda University. Maybe you can call up doctors in your area and ask if they would allow you to shadow?