Less Wrong has a handy feature highlighting comments made since your last visit. Unfortunately, if you didn't actually read all of the comments on your last visit, there's no way to get back the highlight it displayed then. Also, finding new comments requires scrolling, and who wants to bother with that? This extension aims to fix these problems.
Clicking the [-] will show or hide the list of comments. Clicking on an entry in the list will scroll you to it (provided it isn't already on the page).
You can edit the date displayed in the textbox, and the highlighted comments and comments list will update accordingly.