I am still new to this forum, but have spent lots of time and energy at various BMW and Mazda Miata lists and forums over the past 5 years or so. One of the best ways to minimize repetitive posts and questions is to have a section posting articles and FAQs for a broad range of common procedures and failure points involving our cars. For great examples, check out http://www.miata.net
This takes a lot of work and dedication to develop and maintain, but you'll see that most of the articles are contributed by list users and have mechanisms for readers to comment or add to the articles. Certainly it's also easier to develop a comprehensive set of articles for a "one-model" site like Miata.net.
Just my 2 cents worth. I've seen those two sites really flourish and thrive based on a healthy combination of both active contributors and hungry users. Unfortunately from a MBZ standpoint I'm still more of the latter than a qualified former!