Over at the O'Reilly Radar, Tim talks about how book sales track overall technology trends very closely.  I first saw a presentation on this by Tim at the last FOO Camp.  You can draw some very interesting conclusions about adoption of various technologies from their data.  O'Reilly was inspired, at least partially, from Moneyball, which is a tale of using statistics in baseball to pick players that are undervalued by traditional subjective approaches.  I recently wrote in my MIT blog about how the Boston Celtics are doing something similar.  I'm a big believer in tracking and analyzing metrics to help make business and technical decisions.  Anytime I design an IT or software system, one question I always ask: how are we going to measure success through the use of performance and customer satisfaction metrics?  This should not be an afterthought.

BTW, if you think you can get rich writing technical books, just look at how badly the overall book market has performed for the last 2 years compared to 2003 (and 2003 was a significant decline from 2000-2001).  Back in the late 90s and early 2000s (before I got started writing books), you could make quite a bit of money on books that were not considered big successes.  Now, even a top seller in a category is not a guarantee for solid returns.  But alas, I keep writing!