Memento

Memento is a simple to use software solution for creating small notes on your computer, arranging them easily, managing files from the notification area and adjusting settings. It's packed with all sort of interesting tools that you can use and it has more options than the default notes application on some Windows versions.

Lightweight interface that could use some more customization options

Memento is quite easy to install and it sports a really intuitive graphical interface, with the option of creating notes by double clicking on the icon in the notification area. Notes can be enlarged easily and the time and date when they were created is displayed in the upper part of the window.
As opposed to default Windows OS notes, Memento doesn't allow you to pick a specific color for your notes but they do come in various random colors that are easy on the eyes.

Create all sort of notes easily

Memento allows you to move notes around the screen and resize them in the usual ways. Notes normally appear on top of everything else, but you can hide them by clicking the close icon, the note will minimize down to the Memento icon in the notification area.
You can delete a note by shift-clicking the close icon.. If you double-click on the title bar of a note, it will fold up, leaving only the title bar showing.

Adjust options and enable the standalone mode

Left-click on the Memento icon and you will see a list of all your notes, choose the one you want to edit, and it will open for you. The options let you enable/disable colored notes, and choose whether you want to have scroll bars on the notes, configure the hotkey, and so on.
If you want to take your notes with you, Memento supports a 'Standalone' mode, which means that it will look in the same folder as the EXE to see if there is a 'Memento.notes' file there. If it finds one, then it uses it as the notes file.
All in all, Memento is a really nice application that allows you to create all sort of notes, adjust settings and hide them from the desktop screen.