Padlet - Visual boards for organizing anything.

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.

Quizalize - Quizalize is a leading web-based and mobile-based classroom application that delivers the best and easiest way to differentiates your teaching.

Drag for Gmail - Transform Gmail into organized To Do lists (like Trello)

Popplet - Popplet is the simplest application to capture and organize your idea.

KanbanMail - A Kanban board for your emails.