Never took part in one, don't know how it works (just saw that Yahoo offers it, I'm sure there are thousands of other online and office leagues out there). Want to know more about it. So, calling on the experts to see if you'd like to start up a league and I/We will follow.
http://football.fantasysports.yahoo.com/f1/signup - yahoo.
http://games.espn.go.com/frontpage/football - Espn.com
Also, don't forget to teach us newbies how this things work.