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.
Create Issue Branch - Automates the creation of issue branches on GitHub
Nifty - Manage projects, work, and communications in one place.
REVISR - Git Management for WordPress : keep track w/ version control
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.
GitScrum - Project management tool for agile teams.