I have been adding my library books to Evernote. If I place a graphic of a book cover in a note for each book, I get a really nice view of my library using the thumbnail view. However, I cannot add any information to the notes and still retain that nice view of my library. I have worked around this by making the graphic of the book a link to a second note, where I can make my notes and comments on a book. This is, however, quite time consuming and clumsy. It would be much simpler to be able to right click on the graphic in a note and have an option there to designate that graphic as the image that shows in the thumbnail view.
I can see this feature being used for many other collections including music, art, household items, websites etc.
There are programs specifically for book collections etc., but then I have to store my book collection information separate from all my other notes and information. Having one place to store all my information is important, as I suspect it is for many Evernote users.