I've had a few applicants ask me if there is anything to do after being wait listed for medical school. I do recommend streamlined letters of intent that include what makes you a distinctive candidate and updated information regarding your candidacy. I edit these if you want help.
I've also heard of applicants sending letters of intent AND making an appointment to tour the school. A visit demonstrates further interest.
Hang in there. Remember that some people get off the wait list as late as the summer. (Not ideal but better than not getting in.)