SlateStarComments

NOTE: Now unnecessary, as Scott has added this to his blog. The only thing this does which is not provided automatically is the number in the title bar.

Some of the best discussion on the net (if you like a very particular kind of discussion) happens in the comments of Scott Alexander's blog, Slate Star Codex. Unfortunately the thread system doesn't make it easy to see when new comments have been posted. This extension injects a bit of code to fix that: comments posted since your last visit (or a time you specify) are outlined, and a small floating window lists them.

As of the most recent version (1.2), it also adds to every comment a new button next to the 'reply' button allowing you to collapse the comment and all of its children.

Usage tips:
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.