Hygger - Hygger - is an Agile project management tool with built-in prioritization.
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.
KanbanFlow - KanbanFlow is a Lean project management tool allowing real-time collaboration between team members. Supports the Pomodoro technique for time tracking.
GitHub for Atom - Git and GitHub integration right inside Atom
Meistertask - MeisterTask is an intuitive task management and collaboration tool.
Flow-e - Turn your Gmail or Office365 inbox to a Visual Task Board.