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.
Arcade Trail - Crowdsourced game discovery & curation platform
Augmented Steam - Enhanced Steam fork by IsThereAnyDeal.
Rawg - Video game discovery powered by you!
Steam Tools Hub - A set of Steam related WebApps built around trading cards, emoticons and backgrounds.
500 Streamers - A forever changing list of the Top 500 streamers on Twitch