Under the "Objects" pane of the About Land floater, you can see a list of who has objects rezzed on your land, and how may prims they have rezzed. It would be nice to add another column, showing how many URLs they have allocated. I don't see that adding this would be too much of a hardship, as most of the framework is already in place, just a new column in the data field. ;p And I think it would be of great use to landowners to both administer and diagnose possible issues that come up with URL allocation.