At Wayne State, they say they require the committee letter OR three faculty letters. But when I had my interview, my interviewer asked why I did not have a letter from a work or volunteer supervisor since I had done so much in that area. I told him that the secondary said to send three faculty letters so I did! Apparently it would have been okay if i had sent a letter from someone else.
At MSU-CHM, they ask for, and I quote "three letter from individuals". that's as specific as they got. I still sent three faculty letters. I got their secondary, but haven't heard about an interview.
At MSU-COM, they give you two forms, and ANYONE can fill them out except immediate family. They stress ANYONE too, because they want people who know you well.
At U of M, they ask for one non-science and two science letters.
So really, it depends on what they school stipulates. My self-appointed "advisor" ( I say this because I do not like my university-assigned advisor and I also do not like the pre-med advisors) happens to have taught me in three classes. He really was who has advised me on all pre-med type matters, so his letter served as a faculty and pre-med advisor letter for me. I didn't send any letters to any schools that were from an actual "pre-med" advisor.
I graduated from MSU in May of 1999. I stuck around for another year and took a few grad courses, TA'd for awhile, and retook the MCAT, then applied last June. I still live here, but I am moving to Maine in January. (Know anyone who is looking for an apt for next semester? If so, let me know, I need to sublet mine!!)