Complutense University Madrid
Having studied at many private language academies attempting to learn the Spanish language to aid in my stay here in Spain. I was advised to try a course run by the Complutense University (Madrid’s answer to Harvard or Oxford) especially for foreigners wanting to learn Spanish as a foreign language.
So I enrolled for one term, which I found to be quite cheap compared to the private schools and I was immediatly impressed with the level of the professors and the intensity of the course. Seven years on and I still owe it all to this course that changed my broken spanish into me becoming fluent and allowing me to build my life here in Spain.
For information and course timetables/bookings have a look at the following link: http://www.ucm.es/info/cextran/Iprincipal.htm

Great post.
For those looking to spend a summer, semester or an entire year abroad you can also check out the Saint Louis University Madrid. They offer a variety of classes and the faculty is amazing