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.
BMC Software - BMC Software is a solution for companies to help them in running and reinventing their businesses with scalable and modular solutions to IT problems and management.
GoodGantt - The best Gantt chart for Trello®
accurev - version control system. Licensed
Paws for Trello - The best way to use Trello on your desktop
Hex.pm - Hex.