When I travel to foreign places, one of the things I love the most is getting to know the natives and getting a taste of living like a local. Making friends who live in the places where you travel is a great way to educate yourself and to learn how we are all connected by the simple common experiences of everyday life, whether it is laughter, good food, or a beautiful vista.
Couch Surfing is dedicated to cultural exchanges and education through the simple act of getting locals to show visitors their city. The best way to get to know a place is to stay with local inhabitants and couch surfing is like a huge community bulletin board which offers visitors to a city everything from a simple coffee or drink with a native, to a couch to sleep on for a few days. Although all this is all free, it is NOT meant to be a freeloader or extended stay offer; if you are looking for free crash pads, this is NOT the site for you.
Think of Couch Surfing as an adult foreign exchange program; you should respect the host and the host should respect the guests. Hosts are welcoming strangers into their homes (the host decides whether or not to accept a request); this is meant to be a way to build relationships and understanding. People are vouched for by others who have actually met them and references are taken very seriously (this applies to both hosts and guests). People who do not adhere to the principles and ethics of this type of exchange are black listed.
Most places are in the US, but several languages and countries are represented and there are "ambassadors" for several cities. The FAQ section covers various practical tips for women traveling alone, vegans, physically challenged travelers, and people traveling with children.
I found this to be a great idea and if you keep in mind all the common sense rules for travel (like checking references and profiles carefully before selecting a potential guest or host), this could be a wonderful way to travel to new places and make new friends all at the same time!