Walling for Windows - Visual walls for your ideas and projects. Now on Windows.
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.
Microsoft Whiteboard - The canvas where ideas, content, & people come together.
GoodGantt - The best Gantt chart for Trello®
Milanote - Milanote is a note taking app for creative work.
Paws for Trello - The best way to use Trello on your desktop