[itsme]

There's a huge number of metadata fields and probably everyone uses just "his" subset of them. Maybe reusing another, otherwise unused field, might help. The best overview of available fields is in the "Configure Fields" window.
A more general solution would be to add some more custom fields and allow renaming of the custom fields. Currently we have "Custom", "Custom 2" and "Custom Group". Only "Custom Group" can be given a user specific name. A second Custom Group might make sense.