vdNote - Share noteworthy moments from YouTube videos.
Hubub - Host better conversations around video.
Amie - GitHub for research and data science
Bookmark It - Create awesome notes on YouTube videos
Notepin - Extremely simple note-taking + blogging ✍️
Grid Note - Grid Note is an app by Sumi Interactive that comes up with features to help you in adding notes in a grid layout to share your ideas and thoughts with the outside world.