Yep, I wrote (and still use) that. It does two things. On the main page, it puts "(X New Comments)" next to comment links that you've visited. Inside comment

Yep, I wrote (and still use) that. It does two things. On the main page, it puts "(X New Comments)" next to comment links that you've visited. Inside comment discussion pages, it places "New Comment" tags next to new comments. Simple but effective. It uses HTML5 local storage, so you'll need a compatible greasemonkey-enabled browser. Frankly, I wish pg would just add this feature to the site itself...