Okay, now that I'm fashionably late, I can chime in.
With respect to the conversation about "What are we working on?" -- last night when the question was raised, I was doing "research" for a new book project. I call it "research" with quotes because all I was really doing was reading a book that's of a quasi-related subject matter, and is a book I would have read anyway, just for fun. So calling it research is kind of like writing off my cable TV subscription as a business expense. Technically it might have some vague ring of truth in it, but I don't feel quite above board doing it.
This new novel is kind of an odd duck -- an admixture of two things, but neither fish nor foul. To get the idea factory primed I've been reading Will and Ariel Durant's The Age of Louis XIV, though the book is not about 17th century France. And I've been reading Legacy of Ashes: The History of the CIA by Tim Weiner, though the book is not about the CIA.
Now to Chris's "serendipity" question. I agree that it really is one of those "you make your own luck" kind of things. As a writer it's incumbent upon you to expose yourself to just about anything and everything. Like you with the Mayans, I've got pages of typed notes and half of a shelf of books about ancient Mesopotamia for an abortive novel. But that stuff all gets filed away someplace, and eventually I'll be writing something set in the 19th century, and I'll have a character who's an archaeologist, and boom! Guess what? He's an expert on ancient Mesopotamia, and then things start getting interesting.
I think the point is that writing is kind of like doing a jigsaw puzzle where you cut your own pieces individually and try to fit them together based on some vague notion of what the picture is. The more pieces you have in your box, and the more different kinds of pieces, the more likely you are to come up with a compelling and original finished item.
So that leads me to another question. SPEAKING OF abortive novels, how many do you have jamming up your notebooks and/or hard drives, and at what point do you decide, "No, this isn't happening?" How do you know? And how do you know whether it's not the right time to write it, or whether it's just plain no good?