Dropbox Paper - A collaborative document-editing service
NoteAway - NoteAway is the simplest, most convenient way to take quick notes on OS X.
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.
JustNotepad.com - A free online notepad allows you to create any text or notes in your web browser.
Ghostnote - Add notes to anything.
TakeNote - A web-based note-taking app with GitHub sync and Markdown support.