Like Louis I started writing a book[1] after reading Nathan Barry's Authority. I did it mostly as a learning exercise, and boy did I learn a lot. For example, the first email I sent to my list had blue underlined words that were supposed to be links but didn't get linked. Never gonna let that happen again.
Writing and self-publishing books seems like it might be a little faddish lately, but I couldn't be more excited. A book, even a short one like mine[2], lets you expand on thoughts so much further than you can in a blog post or a tweet. I'm delighted to see all of this longer form thinking taking place in our community.