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.
Asana - Asana project management is an effort to re-imagine how we work together, through modern productivity software. Fast and versatile, Asana helps individuals and groups get more done.
TaskBoard - A Kanban-inspired app for keeping track of things that need to get done.
Infinity - Infinity is a fully flexible work management platform where you can organize all your work, your way.
Pintask - Pintask is the most customizable Kanban board.
Zenkit - Zenkit is the home you always wanted for your ideas, your projects, your business.