Reservation abuse
This page ranks users that abuse reservation privileges. Abuse is defined as cancelling, moving, or extending a reservation shortly before the reservation would have started. A point penalty is calculated per abuse. Point penalties increase the shorter the notice of a reservation change. (That is, cancelling a reservation right before it would have started will incur a high amount of points, while cancelling it 6 hours before would incur fewer points).
The weight & details of what constitutes abuse can be configured (though reasonable defaults have been chosen).