The South American Explorers, then the South American Explorers' Club, began with a single simple clubhouse in Lima, Peru in 1977. Then it expanded with another in Quito, Ecuador and in the last decade new clubhouses have opened in Cusco, Peru and Buenos Aires, Argentina. This year, the non-profit organization is celebrating their 30th anniversary.
More than a clubhouse, these are tremendous resources for travelers that should be on every continent. They are a home away from home, a library, book exchange, luggage storage, trip report safehouse, and house of scholarly and not so scholarly resources. There are weekly events and lectures on culture, activities, and history in every clubhouse. Pub quizes, online forums, movies, a kitchen with free tea and coffee. If you want to know how to hike to Vilcabamba, the last Incan city, you ask them and they'll tell you how and where to find the map if they don't have one. If you want to volunteer or take a language class, ask them where and how.
If you plan on spending an extensive amount of time in South America, a membership is highly recomended (plus comes with a subscription to their excellent magazine).
For more information visit their website.