Indigrid - Plain text outliner with side-by-side views.
Scrapbox - A new style of note-taking that lets you create, discuss, and learn together in one self-organizing space.
Alternote - OS X note-taking app for Evernote.
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.
Kirjoitusalusta - Based on open source Etherpad. Finnish language. Supports HTTPS.
Additor beta - Pocket and Evernote got a minimal and collaborative baby