Pretty much any department you pick will probably be mostly scut work. You're just a volunteer, so you can't really do anything else. The most you could hope for anywhere is to take vitals/ekg sprinkled amongst the more menial tasks. Long story short, I don't think ER is any better or any worse than another department for volunteers.
How much you're asked to do probably depends more on who you're working amongst than the department. For example, I've volunteered in an ER for several years. For the first semester or two, there were a couple of nurses who were incredibly psyched to have volunteers, and passed everything they could to us (taught us how to take EKGs, vitals, hook patients up to monitors, etc.), and would pull us into rooms to stand right next to the MD as they did some interesting procedures. When these nurses transferred to another department, all of that enthusiasm went with them. I then spent most of the time cleaning rooms, changing beds, transferring fecal samples, etc., and the nurses/doctors were quite content with this and wanted us to do nothing more.
