I've worked for a publisher of technical books and written a small technical book. They are very very rarely lucrative for the author. However, they almost alwa

I've worked for a publisher of technical books and written a small technical book. They are very very rarely lucrative for the author. However, they almost always bring a lot of clout and usually involve learning a subject at a deeper level than you normally would. So, usually it's worthwhile to write at least one if you have the opportunity. There are a couple of things to keep in mind: 1. Books often challenge an author's discipline and then become extremely painful exercises. With most programming you get regular feedback. Many authors go months without getting any feedback at all. So, be aware, time management is important. 2. In my opinion, longevity of the information you're writing about matters more than anything. The primary benefit of writing a technical book is getting to claim to be an expert for awhile (that and helping people). If you were to write a Javascript book in the O'Reilly cookbook style (how to find the length of an array, etc.) you could expect to be a javascript expert for many years. If you were to write an Android Application Development book, you might only have a year. I published my book (a pocket reference for O'Reilly) in 2003 and landed my biggest client this year because the technical decision maker had a copy on his desk. That's why I'm a believer in evergreen topics. 3. Lucrative means $50-100k. I have a friend who tells a story about how the car he drives came from his first royalty check, $42k. That's a lot, right? Maybe he made $100k on that book for three months of work. But it's not repeatable. The way that it became lucrative for him is that he parlayed that into high dollar consulting and eventually CTO of a well funded database startup. If you're savvy about picking a topic with some interest, you should expect to make $10-20k lifetime. That's less than you'd make in salary. 4. Get co-authors. I think that's the most efficient way to write a book. That way you're not responsible for the entire thing.