I have been working on a project that will result in a book late next year. It will be about the horrific aircraft accident on Svalbard in 1996 http://en.wikipedia.org/wiki/Vnukovo_Airlines_Flight_2801
When I came to the time that I needed to start to write, I soon discovered that I could not start at the beginning and write to the end. It would be bits and pieces and rearranging of more bits and pieces. I searched for a Mac OS software specialized for authors. And Scrivener was PERFECT.
I specially love the research function where I can use a split screen with sources (often PDF-files) in one window and my manuscript in the other. Now I look forward to the next few months with writing.