Coachsurfing - The
very popular non-profit website of people who offers others a free room for the night, week, or month.
Global Freeloaders - The worldwide free accommodation network. Smaller than Coachsurfing, but give it a try if you can't find anyone at your desired location at other websites.
The Hospitality Club - Stay a few days in someone's home for free. With more than 300 000 members, there is a good chance you
get to find a place at your destination.