The Complete Story Behind the Fall of SEOChat is a great blog post by yfs1 (Jason) on how the once-great SEO forum was mismanaged into becoming a massive failure.
If you look at forums.seochat.com today, you will see this message at the bottom of the main forum page: "Most users ever online was 979, February 1st, 2007 at 07:00 AM."
You will also see that this once huge forum now has an Alexa rating very close to the "one week average" Alexa rating of our own two-week old forum.
There are several lessons to be learned from yfs1's analysis of SEOChat's experience.
I believe that the main lesson is this: Listen to your community members. Don't quash criticism -- beg for it. Member feedback is the #1 method for learning how to improve and grow.
The owners at SEOChat deserved their fate.