Steam Charts - An ongoing analysis of Steam's concurrent players.
Fanly - Keep up with all of your favorite sports teams
Steam Database - This tool was made to give better insight into the applications that Steam has in its absolutely huge database.
Starters - Hacker news for sports tech
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.
OverTime - Easy time-overlap tables for remote teams.