I just finished reading The Tipping Point: How Little Things Can Make a Big Difference this morning. Basically, it's about how little things can tip a sickness into an epidemic or turn something into The Next Big Thing (hereafter abbreviated TNBT). There are a lot of interesting points in the book, but there were a couple that struck me as being useful for writers:
People--Three types of people are good at tipping things past the crucial point: Connectors, who know lots of people in different circles and network them; Mavens, subject experts who share their knowledge; and Salespeople, charismatic persuaders. These are the people who can help you network or convince others that your book is TNBT. Certain blogs (such as agent blogs) might be Connectors, and reviewers might be Mavens or Salespeople. Any nominations for specific people?
Groups--The magic number here is 150. When a group gets larger than that, it's impossible for everyone to have personal relationships with everyone else. Some companies and organizations split when they grow beyond this stage.
There's a lot more in this book -- Stickiness, Context, and other concepts--but I'd recommend you read it, since I can't summarize everything in a single blog post. But the overall point of the book is to look for little things that make a big difference. They might not be what you'd expect.