There are definitely a few things you can do while you wait, and update them if you are able to pull any of it off:
1. Get a promotion at work
2. Retake the GMAT and score higher
3. Enroll in a Statistics, Calculus, or pre-MBA style math course
4. Attend school functions (if you live around there) and get to know the admissions director or team.
5. Take on big leadership type pojects or roles at your current job if possible
6. If you are able to complete any of the above, send them an update and continue to show how interested you are. Your goal should be to get your name as HIGH up on that waitlist as possible b/c it might be the difference between getting in and not getting in.
PS. Only send ONE update. You do not want to be the person bombarding them otherwise they will consider you "that crazy guy" and that will definitely earn you a ding. So make sure to be tactful with your only update. So pick the right time, right info, and right way to update them.
If they didn't tell you how to make those updates, then I would contact the department directly and figure out how you can update your information if things have changed since you applied.