For those of you who belong to Facebook (and, if you don't, why not sign up - it's free, fun and useful), there are several groups you might want to join over there that appeal to fans of Classic Mysteries. You can find any of them by doing a search on Facebook for:
The Golden Age of Detective Fiction
"Sherlock Who?" The Ellery Queen Appreciation Society!
Lovers of Rex Stout
As my Whimsy Takes Me
The Roderick Alleyn - Ngaio Marsh Fan Club
I think the fourth of those - the one for Lord Peter Wimsey - is probably the largest, but all of them are worth joining. There are message board and ongoing conversations. If you know of other Facebook groups, or find other groups, that are appropriate for Classic Mystery lovers, please leave a comment and let me know!