I'm not sure if this has been mentioned before in a previous thread (I haven't seen anything), but the other day I was walking around the Salamanca area of Madrid and ran into a small English bookstore. It's kind of tucked away from the main shopping streets, so many of you would probably never have heard about it otherwise. It opened a year ago (last September). There aren't many all-English bookstores in Madrid, so it's always nice to have another place to go. It's between Ortega y Gasset and Diego de León and it's called:
Hartley's Good Bookshop
Calle Padilla, 74
If you happen to be in the area, keep it in mind and enjoy your reading!