Add a way to be able to tag author names, as well as providing some syntax for adding "all books by authors with a given tag" to a collection.
For example, suppose I want to make a collection of all books by authors associated with Princeton Theological Seminary (Archibald Alexander, Charles Hodge, A.A. Hodge, B.B. Warfield, etc.). I would tag each of these authors with a tag -- say "PtonSem" -- and then I could make a collection with authtag:PtonSem, and it would automatically contain all books by all those tagged authors. It would also automatically update if I bought any more books by any of those authors. Of course if I subesquently bought any books by a Princeton author I had previously not owned in my collection, I'd need to tag that author too, but that would be a relatively rare occurrence.
This would be a shorthand way of doing something that could already be done using author:x OR author:y OR author:z, but it would be slicker and would also allow you to easily create multiple collections from the same list of authors (e.g., all books by by people who have taught at Regent College or just commentaries by people who have taught at Regent College, or whatever) without having to redo the OR set for each of them, or edit multiple collection rules if you find out about another author who meets that criterion you'd set up.
I can envison author tags being used for various common groupings of authors (the Oxford Movement, the Inklings), people associated with a certain theological standpoint (Reformed, Dispensationalist, etc.) or institution, etc.
