Knotable - Cut the noise out of busy email threads
Draw.Chat - Anonymous real-time whiteboard with text and video chat.
Scrapbox - A new style of note-taking that lets you create, discuss, and learn together in one self-organizing space.
Microsoft Whiteboard - The canvas where ideas, content, & people come together.
Google Keep - Capture notes, share them with others, and access them from your computer, phone or tablet. Free with a Google account.
Explee - Explee allows you to make eyecatching and interactive animated video.