I only interviewed at one instate school and waitlisted there. I sent in an LOI today b/c i really desparately want to go there. I don't think it's bad to send in an LOI. I talked to a med student on the admis committee saturday and she said definately send in a letter, update them, tell them you're still interested. Mostly to put your name out there so that they remember you when it comes time to move down the waitlist. In mine, I mentioned how it was my first choice and included an update of things that I've done that pertain to why i want to go there.