Momentum - Agile goal and performance management
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.
Minimo - An elegant, simplified new tab page
GoodGantt - The best Gantt chart for Trello®
Notepin - Extremely simple note-taking + blogging ✍️
Paws for Trello - The best way to use Trello on your desktop