Knotable - Cut the noise out of busy email threads
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.
Scrapbox - A new style of note-taking that lets you create, discuss, and learn together in one self-organizing space.
A5 - Takes notes in your browser. Elegant & simple.
Google Keep - Capture notes, share them with others, and access them from your computer, phone or tablet. Free with a Google account.
Draw.Chat - Anonymous real-time whiteboard with text and video chat.