Hacker News Stack - Focus on the really fresh and unread news in Hacker News.
Box Piper Hacker News - Re-Imagined Hacker News for this decade.
The Y Combinator Database - The definitive database of YC companies with all the metrics
Mode Dashboards - Beautiful new tools for tracking and exploring key metrics
HNdeck - Browser for staying in touch with what's happening on HN
Hacker News Front Page Explorer - A database of top ranking Hacker News front page posts