Everfest - A global calendar and search engine for festivals
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.
Find your best festival - Compare the music you follow with 100s of festival lineups
Augmented Steam - Enhanced Steam fork by IsThereAnyDeal.
Hootenanny - Find music festivals featuring artists you love.
Steam Tools Hub - A set of Steam related WebApps built around trading cards, emoticons and backgrounds.