I haven't done a visitor recommendation for quite some time now so it was nice to receive an email from someone last week. Here's what Greg had to say:
I recently found your site and saw that the best bookstore in Madrid is actually not listed on your site. It's a new and used bookstore with a bar/coffee shop attached. It has the best selection of English books in all of Madrid. Over 25,000 books and also different activities throughout the week for meeting new people and hanging out. The place is called J&J Books and Coffee It's located on C/Espiritu Santo, 47 in Madrid's center.
I seriously hope that you will add them to your site because it's the best place there.
Thanks for the recommendation Greg and if anyone else has been there, please let me know.