OneNote - Get the OneNote app for free on your tablet, phone, and computer, so you can capture your ideas and to-do lists in one place wherever you are. Or try OneNote with Office for free.
WriteXO - A cloud based notepad made for writers by writers.
KeepNote - KeepNote: note-taking and organization.
MyTextArea - The world's simplest online text editor.
Joplin - Joplin is a free, open source note taking and to-do application, which can handle a large number of notes organised into notebooks. The notes are searchable, tagged and modified either from the applications directly or from your own text editor.
Notepad - Most simple text editor. Just plain text, saves in .txt format.