**I put this list together over almost 3 years ago. I have stopped updating it, so please do not email me asking me to include your site here.
Building on my last list of sports social networks, 25+ Sports Social Networking Websites, here's an updated list of sports-related social networks that reflects your feedback as well as some other sites I've discovered:
FYI, in some cases it is unclear how many members some of these communities actually have, but I at least wanted to provide this list because I think there is a growing opportunity for certain niche social networks (especially in sports, which is such a huge passion and part of daily life). While some of these sites may die, others will thrive and continue to be "passion hubs" for avid fans and participants of specific sports, teams and leagues.
MyAFL - MyAFL is the official community of the Arena Football League. Allows fans to set up profiles and share videos, photos and blogs.
Fan Voice - Fan Voice is the NBA's official social network. It allows fans to create profiles, connect with other NBA fans and discuss players, fantasy teams and more
NHL Connect - NHL Connect is the official fan community of the National Hockey League and includes groups, videos and photos.
RodeoUp - RodeoUp is the official video community for the Professional Rodeo Cowboys Association.
I Am A Trail Blazers Fan - The Portland Trail Blazers were the first NBA team to launch a social networking site. The site allows fans from all over to connect with each other and includes a non-profit/charity element that allows people to volunteer for projects to help improve the community.
Planet Orange - Planet Orange is the official social network for Phoenix Suns fans. Planet Orange "Citizens" can post pictures, videos, blogs; join groups; and chat about the team on a message board.
MyColts.net - MyColts.net is a community that allows Indianapolis Colts fans to connect and show their Colts pride. Includes blogs, photos, surveys, groups and Colts Cred, a points system that gives fans incentive to use the site and create good content. Has over 16K registered users.
Broncos Country - Broncos Country is an online community for fans of the Denver Broncos. Similar to MyColts, fans can earn points for posting pictures, videos and blogs and will eventually be able to redeem them for exclusive access and team merchandise.
HuskerSpot.com - HuskerSpot.com is a community for Univ. of Nebraska sports fans. Users can create a profile, watch videos, view pictures, write in personal blogs, and discuss Husker sports.
FanNation - FanNation is a general sports social networking site tha has a news and stats focus. Its partners include Sports Illustrated and CNN.
Fanspot - Fanspot is a sports social network that features fan clubs, blogs, team stats and photos. The site's design could be better.
iLovetoPlay.com - This site is a meeting place where sports participants and organizations can find each other, communicate. Users can organize sports activities, find a training partner, and find places to play.
FreetheFan.com - FreetheFan.com is a place for sports fans to create profiles and debate sports headlines, win prizes and share opinions and videos.
SportsMates - SportsMates is a global sports social networking site that includes 1000s of communities, blogs, fan directories and photos.
isporty - This sports social network is for general sports fans and is built on the premise that sports is a major force in connecting people.
Comenplay.com - Global sports social networking site Comenplay.com brings athletes together so they can improve their health and fitness, meet new friends and play more sports.
Sportsvite - Sportsvite is a community that includes tools to help people organize pick-up games, find other players and keep track of stats and team events, such as practices and games.
UltraFan - UltraFan is another general sports community that allows people to participate in message boards, post and comment on pictures, videos and profile pages.
Fanzak - Fanzak gives members personal homepages with scores, team news, weather, friends lists, and a place to share their thoughts
sportme (coming soon) - sportme is a UK-based sports social network that focuses on individual athletes, teams and clubs.
ZexSports.com - ZexSports.com is a community for extreme sport athlete and fans. It includes sports such as BMX biking, river rafting, rock climbing, wake boarding and kayaking.
Sk8site - Sk8site is a community for skateboarders to share videos and pictures. Includes skaters such as Jereme Rogers, Transworld's 2005 Rookie of the Year.
Surfspot - Surfspot is a yet-to-be-finished social networking for surfers. Coming soon...
Motocross.com - Motocross.com is a portal site that includes community elements such as video and photo sharing.
High School Sports
TAKKLE - TAKKLE is a high school sports social networking site where students, athletes, coaches, and fans can share their passion for sport. Sports Illustrated is an investor and offers its Top 100 High School Football Player Rankings on the site.
TRU Preps - TRU Preps is a social networking site for high school athletes that was started by MaxPreps in the summer of 2007 and gives high school athletes a profile page for their sports achievements, stats, photos and video highlights.
High School Playbook - This site allows high school athletes and fans to discuss high school sports and share pictures and videos.
SkiSpace .com - Founded by skier Bode Miller, SkiSpace.com provides members with the ability to share user generated content such as mobile photo uploads, skiing action videos and ski lifestyle videos. Site is coming soon (expected winter 2007).
SkiNet - SkiNet allows skiing enthusiasts to create a profile, upload pictures/videos and find other skiers to connect with.
Gyminee - Gyminee lets you to track your workouts and results, join others who are fitness-focused and brag to your "GymBuddies" whenever you reach one of your goals.
Nike+ - Nike+ is an online community where runners can download and share their workout music mixes, track your times and results, and compete/talk trash with other Nike+ runners.
FitLink - FitLink calls itself "social fitness." The site lets you find workout partners, track your workouts and find gyms in your area, in addition to the standard social networking elements.
Walker Tracker - Walker Tracker is a place for walking enthusiasts to track their steps and compete with friends or one of Walker Tracker's mythical characters.
Access Athletes - AccessAthletes is a professional and social community that connects athletes, agents, and the media across the globe so that they can communicate with each other more effectively and efficiently. The site is also open to the general public.
iStadia - iStadia is the global networking, marketing and information service that brings together sport and exercise professionals, sports businesses and athletes.
Infield Parking - Infield Parking brings together race fans and allows them to connect and share pictures, photos, videos and blogs with their friends and fellow racing fans.
GolfLink - Golf Link is an online community for golfers. People can create profiles, view tips, articles and videos geared at helping improve their game, and check out descriptions of over 20,000 golf courses in the US.
FootyHeads FanSpot - FootyHeads FanSpot is a community for fans of Australian rules football to connect and share content online.
Angling Masters - An online community for avid fishermen, Angling Masters lets individuals build profile pages ("cabins") and gives businesses pages ("marinas" and "lodges") to promote their products and services.
OleOle - OleOle is an online community for football(soccer) enthusiasts all over the world. Incudes pictures, blogs, videos and opportunity to participate in a fantasy game.
UltimateFrisbee.com - This is a portal site for Ultimate Frisbee fanatics that includes videos, photos, groups and message boards.
SwimRoom - Launched in early 2007, SwimRoom is a online community for swimmers that includes swimming-related blogs, podcasts, photos and groups and support from athletes such as Katie Hoff and Michael Phelps.
BikeSpace - BikeSpace is an online community for bikers, allowing them to create profiles, share photos and map their favorite routes.
Sixer - Sixer is the social network for fans of cricket.
Sports and Social Bookmarking and Others
Ballhype - Sports community that pulls in content from thousands of sports blogs. Similar to Digg, users can submit their own stories or "hype up" other stories; if the story gets voted on enough, it will make it to the front page.
Deadspin - Sports blog community that offers a non-politically correct (and hilarious) approach to sports blogs, news and stories.
YardBarker - Yardbarker is an aggregator news site that pulls in user-generated content to offer people a hub to consume unfiltered sports news and stories. Individuals can submit articles, vote on them and leave comments. Some of the athletes who post regularly on Yardbarker include Carmelo Anthony, Greg Oden, Baron Davis, Ray Lewis, Donovan McNabb and John Lackey.
SportsAG - SportsAG is a "Digg-like" sports news/blog aggregator that lets people submit and vote on sports stories.