Yesterday I downloaded Jeff Rivera's 99-cent e-book, Effortless Marketing: How I Sold Thousands of Ebooks, Landed an Agent and Book Deal in Just 10 Minutes a Day Using Message Boards. Today I spent two hours in a doctor's waiting room with my Kindle and read the book from beginning to end. Other than a couple of small blips, it's a decent resource for us indie authors.
As its title suggests, it focuses on how to effectively use message boards, stressing the importance of visiting boards with 5,000 to 10,000 users. Of course, different writers will likely have different audiences, but I wish the book gave at least a few examples of large boards. If you know of some, please reply to this post with the information. In the meantime, here are the most promising links I've come up with:
The Big Boards site has a comprehensive-looking list on various topics and in various languages. If I find specific links on that site that seem promising, I promise to share and hope you'll do the same.