LameXP - LameXP is an Audio Encoder Front-End, a graphical user-interface for a number of audio encoders.
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.
Multi frontend - Multi frontend is a Windows GUI (grafical user interface) for the following console audio...
Augmented Steam - Enhanced Steam fork by IsThereAnyDeal.
FLAC Frontend - [No longer maintained, but downloadable]
Steam Tools Hub - A set of Steam related WebApps built around trading cards, emoticons and backgrounds.