Discovered Try Tag Rugby in my local park, after approaching a player to find out how to get involved I was invited onto their team. It has been a fantastic way to meet new people and keep fit at the same time.
Leagues are really well organised with a good social scene after games. Many social teams play for fun so get involved regardless of your fitness levels or experience. I'd say it's a number one way to make friends and have fun in a friendly sporting community.