OpenXava - OpenXava is a Web Java Framework for Rapid Development of Enterprise Applications.
Trello - Infinitely flexible. Incredibly easy to use. Great mobile apps. It's free. Trello keeps track of everything, from the big picture to the minute details.
Vaadin Framework - Vaadin is a web application framework for Rich Internet Applications (RIA).
GoodGantt - The best Gantt chart for Trello®
Apache Sling - Apache Sling is a REST based web framework,
Paws for Trello - The best way to use Trello on your desktop