snail mail a letter to the DGS at each school, thanking them for considering your app, and letting them know that their program is one of your top choices. in the letter, be sure to maintain a grateful disposition for your placement on the wait-list, and include all your contact info in the case there is something you might be able to do to improve your chances of receiving an offer.
i tried this at a couple of schools and received personalized emails from each DGS, thanking me for the letter, and telling me that there is a very good chance they will make an offer to me by mid-april.
good luck!