Idea: A book/magazine exchange.
Procedure: Approach a cafe or bar owner in central part of city about a method to attract lots of gringo cliental (although I find Argentines are often hostile to good ideas to attract gr. ingo clental) about keeping a shelf in the corner of the room for an English book exchange (take one, leave one). No problems for him, but assure him/her he will attract waves of good, new clients within weeks. Explain that the publicity will be free. Leave monthly posts on Lonely Planet for people travelling through. If the dueño is smart, he would drag a shelf out the back and put it in immediately, it would be no work for him, there is no administration. Would be a good place for informal get-togethers also.
Perhaps posters here have such a place and could volunteer their place for the mini-installation. Perhaps such a place already exists that I do not know about. Many hostels and Spanish schools have this service for clients.
I would do it myself, but live in Mendoza.