Epic Pen - A windows tool for drawing over your desktop and applications
Vabotu - More than slack. More than Trello. FREE.
gInk - An on-screen on-screen annotation software for Windows.
Kurator - The premier Chrome extension for savvy researchers and publishers alike. Curate your interest and publish to your website, newsletter and social media sites directly from the browser.
Gromit-MPX - Create annotations by directly drawing on your screen.
Sensive - Design collaboration for everyone