Elegantt for Trello - The most elegant way to manage your Trello projects
Ollert - Learn what your Trello boards aren't telling you
GoodGantt - The best Gantt chart for Trello®
Vacation Tracker - The easiest way to track your team’s vacations and days off.
SendBoard for Trello - Receive and reply to emails in Trello
Punchtime - Nifty time tracking for Trello users and teams