International Police Association - This organization includes a Hospitality Club for retired and active law enforcement officers. - http://www.ipa-usa.org
Global Freeloaders - Online community matching guests and hosts for accommodation exchange. Testimonials, FAQs, and a member database. - http://www.globalfreeloaders.com
Friendship Force - Nonprofit cultural exchange organization promoting friendship and goodwill through an extensive program of homestay exchanges since 1977. - http://www.friendshipforce.org
Couch Surfing - Network connecting travelers with locals offering accommodations and advice. Members can be vouched for by other members or verified by paying a fee. Includes information about the organization, searchable database, message board, and chat room. - http://www.couchsurfing.com
Hospitality Exchange - Publishes a paper membership directory twice a year, there is a membership fee. - http://www.hospex.net
Hospitality Club - Volunteer members offer free accommodation and travel help and leave comments in each others' profiles after the stay. Includes a forum, chat, and wiki travel guides. - http://www.hospitalityclub.org
MeetURplanet - Australia-based club. Registration is free but paid membership is required to contact other members. - http://www.meeturplanet.com
Place2Stay - Offers a worldwide network of private accommodations. Includes information about accommodations, a forum, FAQ and chat room. - http://www.place2stay.net
Pasporta Servo - For people speaking Esperanto. There is a membership fee. - http://www.tejo.org/ps/
Welcome Traveller Network - Members pay a nominal fee for bed and breakfast when visiting other members. There are several interest groups. - http://www.welcometraveller.org
Warm Showers List - List of cyclists who offer their hospitality towards other touring cyclists. - http://www.rogergravel.com/wsl/vh_for_a.html
Women Welcome Women World Wide - For women only. Aims to foster international friendship by enabling women of different countries to visit one another. There is a membership fee. - http://www.womenwelcomewomen.org.uk
Teachers Travel Web - Open to all educators. Site also includes home exchange listings. - http://www.teacherstravelweb.com
Servas International - Oldest hospitality exchange organization. Website includes a newsletter, FAQ and list of countries. There is a membership fee and new members are interviewed by Servas representatives. - http://www.servas.org/