Simple suggestion. I would love if we could store our books in bookcases in our housing. That would be awesome for RP etc, or just displaying that assignment you got an O+ on 
I wonder if it would be possible to have a block or something placeable that players can use to bring up a GUI of stored books -- similar to how players would be able to get books from the Library awhile back. The owner would be able to do a command such as /books and store any books that they have.. then this block that gets clicked can also show the stored book items in a GUI for other players to see.
The /books command would be for the owners whilst the bookcase block to click on would be for everyone else.
Then this system could be expanded to trade or sell books.