http://sportsvite.com/
This is a social network website dedicated to sports (think MySpace for
recreational sports enthusiasts). It aims to help "Discover, organize
and participate in recreational sports activities".
It sounds interesting, plus they do have a badminton page:
http://sportsvite.com/sports/Badminton
You can also search for other badminton players by city, there's quite
a few baddy players listed for the DC area!
- Aamir