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.
Ansible - Radically simple configuration-management, application deployment, task-execution, and multi-node orchestration engine
Nifty - Manage projects, work, and communications in one place.
Jenkins - Jenkins is an open-source continuous integration server with 300+ plugins to support all kinds of software development
Jira - The #1 software development tool used by agile teams. Jira Software is built for every member of your software team to plan, track, and release great software.
Puppet Enterprise - Get started with Puppet Enterprise, or upgrade or expand.