Penflip - Typewrite is a real-time collaborative writing environment with Markdown support, versioning and Dropbox syncing. Alternatives to Penflip for Web, Windows, Mac, Linux, iPhone and more.
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.
Cleartext - A text editor that allows only the 1,000 most common words
Simplenote - The simplest way to keep notes. Light, clean, and free. Simplenote is now available for iOS, Android, Mac, and the web.
Quill - Powerful, API-driven rich text editor
Evernote - Bring your life's work together in one digital workspace. Evernote is the place to collect inspirational ideas, write meaningful words, and move your important projects forward.