Write to them. Send them a thank you card (personally made up, handwritten, even handmade, if you can make it look good) for reading your application and taking the time to consider you. Send them food. Everyone loves food. Make an effort to go there and tour, and mention to your guide that you've been wait listed.
A lot of college admissions centers have a bucket of people called "clamourers"--people who, even though they were waitlisted, have still shown extreme interest in going to the college. When they go to pull someone up from the wait list, they go to the people in that bucket first.