I think it's a fantastic idea. I suggest also adding the possibility of allowing people to create accounts with their email so they can add in their Kindle ema

I think it's a fantastic idea. I suggest also adding the possibility of allowing people to create accounts with their email so they can add in their Kindle email addresses. I would also suggest allowing users to view previous/archived articles from each group in case they aren't sure if they really want to join the group or not.