You can take note with this plugin. It shows up under content editor. Notes won't appear on actual pages. So visitors can't see your notes.
The Live Video Annotation plugin allows you to add timed footnotes to a YouTube video. Visitors can see these notes later while watching the video.
Documentation is now easy way.
Author's Note allows you to add author's notes and after-thoughts to your blog posts and pages.
With this plugin you can warn other wp-admin users. For example, you can type “Don’t touch widgets! I’ll fix it tomorrow !”
Allow readers to highlight and bookmark POSTs with simply highlight buttons. Easy to add personal notes on POSTs and share.
Image tagging system sync with WordPress comment system. Or also known as image notes, or image annotation.
The most lightweight yet customizable cookie plugin with hook based settings.
Rombus Shortcodes plugin used for shortcode purpose in Rombus WordPress Theme.
Plugin add backend note fild to all comment
Simple Note Widget is a Quick Note Display widget for a website.
Allows you to add textual annotations to images by select a region of the image and then attach a textual description.