From the days of 1200 baud modems dialing into Prodigy, I've enjoyed the banter on the Diamond Club. I can follow the news in other leagues if I choose - sometimes find some good FA tips that way - and the discussions in the Bar and Grill are lively, and sometimes just silly (occasionally both!)
I also like that the DC is open to anyone who cares to register. So even if you're not enrolled in a league, you can still stop by and check things out over here.