Sidenote is a simple and original note-taking application which is activated when you hover your mouse on the left or right side of your screen. To create a new note, simply click on "New Note" and, then, select a name, and the note's color. Apart from text, the notes can also contain images. To add an image, simply drag it to the program. If you want, you can also import an image from your scanner or web camera. Moreover, the notes can also appear in the form of sticky notes to have them on your desktop. For the text, you can customize the font style, size, type and color.
The lists of notes created will appear on the upper part of the screen with their respective names and colors. Sadly, the program doesn't include a search dialog to search for notes more quickly by entering keywords, and you won't be able to separate your notes in different folders or categories. Moreover, the program can be pinned, so it will remain visible all the time and you can also send the program to the other side of the screen with the click of a button.
Briefly, if you are looking for a very simple program to create notes, Sidenote may be good for you.