research the company. if anything strikes you during the research, make a note of it and ask. ALWAYS RESEARCH. there were some girls coming in to interview for positions here at my company and they knew NOTHING about us other than we were an ebay company.
- see if you can get a "typical" work day. or if there's no "typical" day ask about what challenges they have during their day
- possibilities for advancement. look at the long term - if i stay on through college, do you have programs for hiring interns who have been here forever, etc. also if you want to move into other departments are people open to it.
- how long does a person typically stay in a position before they get promoted up
- if they haven't gone over it, or ask them to elaborate on responsibilites. how many people do you report to, stuff like that
never ask things like salary, vacation, etc. that's more of what you can get from the job instead of what you can give to them. you're selling yourself as the best person they want, not someone who will poke along and just get paid.