Websites on Partner Finding:
Adventure Contact
Collection of Yahoo groups intended to match activity partners.
Buddyup
Find another person with the appropriate skill doing your sport in your area. Over 20 sports including running, biking, skating, golf, tennis, and skiing.
Match Maker
Find a player, team or partner to play with by registering.
PlayerLists.com
Free service allowing any amateur player of any age to find a team in many sports. Visitors can post "Player Resumes" or "Team Ads" and be notified when a match is found.
Women's Exercise Network
Locating partners for a variety of sports, primarily for women. United States.