Any Addons that aid in Library Cleanup and/or metadata repair/cleanup?

[Meido]

As per title, are there any good addons that can aid with and/or do the following (I know that Calibre can do some of this inherently, but I'm looking for other/better options):

-Find and compare "duplicates"
-Manage duplicates
-Use a books ISBN to acquire metadata
-Find books with specified metadata (eg. tags, author, publisher, etc.) missing
-Take what metadata you currently have to find your missing metadata

I guess one of the key things I'm wondering is what is one of the best/accurate ways to find/get missing metadata?

[theducks]

Have you looked at the Plugins index (descriptions)?
Most of your requests have PI with those descriptions.

As to your last item: Calibre uses existing metadata as part of your search.
I believe ISBN is giveen priority, with a title-Author as fallback

[mbovenka]

Originally Posted by Meido

As per title, are there any good addons that can aid with and/or do the following (I know that Calibre can do some of this inherently, but I'm looking for other/better options):

-Find and compare "duplicates"
-Manage duplicates
-Use a books ISBN to acquire metadata
-Find books with specified metadata (eg. tags, author, publisher, etc.) missing
-Take what metadata you currently have to find your missing metadata

I guess one of the key things I'm wondering is what is one of the best/accurate ways to find/get missing metadata?

Well, the 'Find Duplicates' plugin does what it says on the tin.

The rest Calibre itself already does. It uses the ISBN to find metadata, if your book has one. The 'Extract ISBN' plugin will dig through the book to find an ISBN in it if it does not.