Crossfilter - Fast multidimensional filtering for coordinated views
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.
Diagrammm - Fundamentals on data visualization
Augmented Steam - Enhanced Steam fork by IsThereAnyDeal.
BestShot - Your AI-based tennis coach
Steam Tools Hub - A set of Steam related WebApps built around trading cards, emoticons and backgrounds.