NoteIt lets you create useful and private notes on webpages which will be there once you return to the webpage. You can also hide or delete the note once you are done with it. NoteIt comes with a simple toolbar button that helps you create a note with just a simple click.
NoteIt is secure and does not insert your notes into the webpage to display them. This means that even if the webpage is looking, it cannot potentially capture your notes and transmit them off your computer. NoteIt displays your notes in a layer over the top of the webpage, so it'll never know they're there, and you'll never know the difference.