Sortd - Rated the #1 App for Gmail
The Hit List - Your life is complicated, but managing it doesnt need to be.
KanbanMail - A Kanban board for your emails.
Todo.ly - Todo.ly is an intuitive and easy to use online Todo list, and Task Manager. It helps you to get organized, simplify your life, and to get things done. Create todo lists, and manage them online from anywhere.
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.
Planisware Orchestra - Planisware Orchestra is a best-in-class project portfolio management software and solution, providing an agile approach to bring all the stakeholders on the same page.