Keynote is a flexible, multi-featured tabbed notebook, based on Windows standard RichEdit control. It's always accessible with a single keypress, even if you work in another application. Take a look at the screenshots page.
The basic idea in KeyNote is that you can include many separate notes within a single file. This means that you do not need to open several files - for most purposes it is enough to create only one file and hold all your notes inside it. With the addition of the tree-type notes, you now have a three-dimensional notebook: many notes within one file and a multi-level, nested pages within a single note. Optionally, KeyNote can encrypt your data securely using the Blowfish or Idea algorithms. Keynote's interface and behavior are extremely configurable.
KeyNote was written to overcome major limitations in other popular information managers, both free and shareware. KeyNote is the only information manager that offers a combination of simple and tree-type notes, rich text editor, ability to mix freely many notes of different types in a single file and secure encryption. This makes KeyNote the most flexible and one of the most powerful applications of this kind currently available. Some functions, such as "virtual nodes", per-file configuration settings, multiple backups or WordWeb integration are unique and, to my knowledge, not supported by any other notebook program, freeware or shareware.
Editors Note: Because the Keynote project has been abandoned, this download includes the last released 1.65 version, the upgrade to 1.65 and the source code. The end user only needs to run kntsetup.exe found in the zip file.