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.

TaskBoard - A Kanban-inspired app for keeping track of things that need to get done.

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.

LeanKit by Planview - See how Planview LeanKit enables engineering teams across all levels of the organization with a visual work delivery tool to apply Lean management principles to their work, helping them work smarter and deliver faster.

Basecamp - A simple and elegant project management system.

My Personal Kanban - This is a one page HTML/JavaScript application for people who would like to use simple and basic...