Here's the use case:

An event fills up. More people want to attend, and they want to be put on a waitlist so that when a spot opens up, they're the next to get it.

Currently, the process is: Get on the phone with the waitlist person, tell them to pull up the event page. Open signups for the event. Now, quick! refresh the page. Do you see the "Sign Up" link? Go! Go! Go! Sign up now, before anyone else does!

This is not sustainable.

Ideally, there would be some sort of placeholder, like the temporary signup that occurs when a person hasn't quite gone through the checkout yet. Then, when the space opens up, they get an email, and maybe a configurable amount of time (1 day, 8 hours, whatever) to sign up before they're booted and the next person gets it or it opens back up to the public.

Another way to do it would be to have some sort of invite system where the event is closed to everybody except invites. Then you enter an email address and it sends an invite to that person who can sign up for the event and pay and everything.