Navigate your own browser bookmark and see which subjects you actually browse on a regular basis or have developed a certain knowledge about.
I get it lol...thus the sorry state of the internet and the plethora of crap which can be found on it. I just figure I need to keep trying and if just one person realizes things and actually creates a decent site as a result, then I guess it's worth the head-banging. At some point there will become a critical mass of crap and the SEs will end up doing something about it.
I thought this thread was going to be as useful as asking writers where they get there ideas, but instead that has been a good thread, I went ahead and signed up for that daily email form nicheaday.com. Of course, real life abounds with possibilities. I am always tearing pages from magazines and jotting notes from TV news shows, etc. But one source not mentioned here yet is to notice what you dream about. Sometimes a nice message will appear in your dreams.