Steam Charts - An ongoing analysis of Steam's concurrent players.
GameTree - Discover the friends and games you will love most.
Steam Database - This tool was made to give better insight into the applications that Steam has in its absolutely huge database.
Instant eSports - Get the latest eSports news, scores, and stats anytime
Steam Inventory Helper - Steam Inventory Helper is a free browser extension for Google Chrome that adds a big amount of new features into the Steam trade-offer system & Steam store functionality.
Retrobit Game - A monthly subscription box of retro video games