I've been working on and off on this for a little while, the extension focusses on improved usability rather than design. I can almost guarantee that after a day you won't want to go back to regular Hacker News. Give it a try, features include:

- Improved readability

- Quick inline replies from comments page

- Quick profiles with social network info when hovering over usernames

- Filtering of stories based on terms and phrases / domain or user (try filtering out negativity!)

- Endless scrolling

- Collapsible comment threads

- Social sharing for Twitter, Facebook, Google+, Buffer

Forks, improvements and comments always welcome: https://github.com/tommoor/HackerNew