To add to the other tools listed here. I like the free Cherry Tree tool. It lets me set up nicely nested categories and under that set up code folders and notes

To add to the other tools listed here. I like the free Cherry Tree tool. It lets me set up nicely nested categories and under that set up code folders and notes folders. All saved in a single file. http://www.giuspen.com/cherrytree/ http://www.giuspen.com/cherrytree/