Sites suggest that hospitality is not just a way of traveling on a budget, but it is much more, is the opportunity to meet local people in a safe, a real contact with the customs and traditions, who better than a local can give you excellent advice about their country? None
Couchsurfing
Lingua: 
 
 
Perhaps the best site of hospitality, you can do a thorough search and you can see references of people, so there is more safe.
Hospitality Club
Lingua: 
 
 
A good site to find hospitality.
Be Welcome
Lingua: 
 
 
Hospitality in the world.
Night Swapping
Lingua: 
 
 
Is an exchange site hospitality worldwide.
Bed and Lern
Lingua: 
 
 
A particular site where travelers who teaches something and learn something from guest hosts.