TaskBoard - A Kanban-inspired app for keeping track of things that need to get done.
buckets.co - Feature rich kanban board collaboration platform.
Pintask - Pintask is the most customizable Kanban board.
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.
yodiz - Yodiz is online Agile Project Management tool, consisting of Product Backlog Management, Kanban Scrum Board, Issue Tracking Software, Team Discussions and Git/SVN Integrations.