I would love to be able to recommend a book to specific friends. I don't mean a generic recommendation, but I want to be able to send a notification to a friend with a recommendation for a specific book, and to even leave a message on why. It would be really cool for that message to then show up on the book page or their reading history page for that book, so if a book is recommended by several people they can easily view those recommendations.

This came up because I have a SG friend who loves unreliable narrators and I found a great book I think she'd love but I have no way to tell her about it.