I first wrote about the CouchSurfing service on my Eyes On Brazil site but the post can pretty much be applied to any country. In basic terms, CouchSurfing allows you to find a place to crash while traveling or even to offer a place for others to crash, usually for a few days only. The point is to bypass hotels and more formal guided tours in place of having a local fill you in on what is good and what isn’t.
Here are some stats on the Colombia groups on the site. The country group has almost 9,000 members and 4,000 posts. The Medellín group has over 1,000 members, but 8,000 posts and the Cartagena group has 300 members and 2,000 posts. Basically, if you need info on the place you’ll be traveling to and want to bypass the aforementioned tourist traps, sign up and join a group! They are a friendly bunch although they tend to answer posts centered on traveling more so than some specific question about Colombian history or music, let’s say.
Here are some other groups offered on the site.
Santa Marta, Taganga y Parque Tayrona
Here’s an article in El Espectador on CS (in SP)