Remembers which links on Reddit you've seen (even if your browser history don't) and can open all unseen in new tabs.
This extension will remember and mark all the links you've visited on reddit. This is useful when your browser remembers only some small number of visited links and when exceed that limit you cannot distinguish visited links from the new ones. If you browse a lot it gets frustrating.
As a bonus, this extension adds a button that can open all the links from current page that you did not visited (in new tabs).