This may have already been suggested, but I think it would be nice if the names of the pets that have been dead for a very long time and the names of pets that belong to permanently banned accounts were made available again.
Also, this just occured to me; when pets are released into the forest, their name could also be reset. Then, when a creatu is found in the forest, it can be re-named by whoever found it. If that makes sense.
For example, if I just released chucknorris652571 the sepia veram into the forest, the name chucknorris652571 would become available again. Then, if someone found him in the forest, they would just find a male sepia veram and could give him a new name.
It might make forest-exploring boring, but it has its upsides.