One thing I've noticed the past week on goodreads, that could have been their earlier, is a section where they are asking authors if they would be prepared to pay for premium accounts and how much, for stuff like being able to contact readers about events, new books releases and the such. I never responded, and kept thinking it would be just opening up the door to spam. My guess is though, they would make it opt in from readers, but I could think of nothing worst than receiving hundreds of emails from writers flogging their books and imagine I would only select a few writers to hear such events or promotions - so in affect my guess is as a writer any monthly fee would just be a waiste of time, unless you were already very successful.