I'm pretty sure that you could do that with org-mode…
CLI, Linux.. emacs (!). I'm not sure I could manage to grasp emacs during the middle of a really good day much less a quick note at night
Picking up some sarcasm in your comment, could you ask the questions or make the statements you're hinting at and I'll be happy to discuss!
No sarcasm in my statement at all. For the past several years, I've been looking for a personal knowledge management application that would work for me and now I'm seriously thinking about just writing it because I can't find one.
I'll probably write one even if I can't make a business out of it, because I need it. I'm also curious about the business potential and have been asking people in my personal network.
Evernote's pricing seems like a good benchmark - I heard that from several people already.