I think it would be an extremely useful tool to be able to relocate a registrants from one registered event to another, without to manually go into the database.
I currently have a situation where a registrant accidentally signed up for the same paid event twice. What they really wanted to do was sign-up for two different events. It would be nice to be able to simply change an event a registrants is in simply by selecting a different event for them from a drop down menu.