Highlighter Pro: A Medium.com-Inspired Text Highlighting and Inline Commenting Tool for WordPress

Highlighter Pro lets you highlight the text directly on the page and add notes and comments inline with your highlights. You can save and delete your highlights, view all of your existing highlights, view other reader’s highlights, and view conversations inline that other readers are having about your content. It comes with a full statistics engine that keeps track of trending posts by number of highlights, number of notes, number of total highlighters, and many other metrics to sort your posts by. It works on posts, pages, homepage, archive listing page, and custom post types.