This is a really powerful video (less than 5 minutes) compiling feedback from administrators of different schools located around the nation on the impact of school librarians. It was posted on the AASL forum yesterday and was created by Judi Moreillon, who is known for her advocacy of school librarians. This would be a fantastic resource to share with principals and other supervisors!
*Personal side note, feel free to take or leave it: the only two aspects I really wish they had tweaked were the consistent reference to librarians in the feminine (as we all know we have some rockstar guybrarians in our midst!) and the emphasis on school librarians as the Most Important Person. We are each free to have our thoughts on this, but personally I don't think that touting ourselves as the most important members of our faculty is beneficial or accurate. We are equal partners with our teachers and administrators and students and support staff...we just have unique training that helps us fill some special roles!