By useful and/or entertaining, I mean:
You've asked a question and gotten a good quantity/quality of responses.
The forum has frequent postings.
The forum has a sufficiently high population as to keep the signal to noise ratio tolerable.
Just curious. I used to subscribe to a bunch, but only this community seems to satisfy all of the above; this was a couple years ago though, so I'm curious to know what else is out there Now.