Gantt - Create beautiful Gantt charts
Elegantt for Trello - The most elegant way to manage your Trello projects
GoodGantt - The best Gantt chart for Trello®
Hello Epics for Trello - Simplify your Trello board with parent/child relationships
GANTTplanner - Turn your Google Calendar into a Gantt chart
TunnelVision - See your next Trello tasks every time you open a browser tab