Seeing one Topic-X post will trigger many people to think, "Oh, and I remember Y-related-to-Topic-X," as well as "Hey, I wonder if I could find out more about Y

Seeing one Topic-X post will trigger many people to think, "Oh, and I remember Y-related-to-Topic-X," as well as "Hey, I wonder if I could find out more about Y-related-to-Topic-X," and away you go. Also, http://www.amazon.com/Bursts-Hidden-Pattern-Behind-Everything/dp/0525951601 http://www.amazon.com/Bursts-Hidden-Pattern-Behind-Everythin... (even though it is not a great book; it is mediocre IMO).