Document viewer with media library?

[harlan]

I'm looking for a document viewer with a media library in the way the music players have. That is, I would like to import a folder containing documents and then organize them into categories, with the option to search and filter results inside the collection.

Is it posible to add metadata in documents as audio tags do in music files?

I find such application very useful for collections of hundreds or thousands of documents. Anyone knows a document viewer with a media library?