Book Chapters
This is an excellent way to get good book ideas. You will probably have a better sense of what could be expanded on if you are well read on a particular subject. Do you read any books on a particular subject from different authors and notice that they seem to skim over a particular topic and you are still left with questions in your head after reading it? Or, are you simply more interested in that particular aspect of one of your favorite books and feel like doing an in depth study on it? This is a great way to find book ideas. Start with your own books and browse through the chapters. Take note of any chapters that perk you up. Hit the book stores and libraries. It probably won’t take long for you to find an idea for you to seriously consider.