Stonk Journal - Free easy to use trading Journal.
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.
TraderSync - Biometric trading journal to trade without emotion
Augmented Steam - Enhanced Steam fork by IsThereAnyDeal.
Trader's Little Helper - Traders of lossless compressed audio files (e.g.
Steam Tools Hub - A set of Steam related WebApps built around trading cards, emoticons and backgrounds.