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.
Slack - A messaging app for teams who see through the Earth!
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.
Smoothboard Air - Smoothboard Air is a collaborative interactive whiteboard application for iPads and Android devices that revolutionizes interaction in lecture rooms.
Google Keep - Capture notes, share them with others, and access them from your computer, phone or tablet. Free with a Google account.
Groupboard - Free collaborative online whiteboard, web conferencing and online tutoring software that can be embedded in your own website. Used by many online tutors, schools and universities.