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.
SourceTree - Mac and Windows client for Mercurial and Git.
Create Issue Branch - Automates the creation of issue branches on GitHub
SmartGit - SmartGit is a front-end for the distributed version control system Git and runs on Windows, Mac OS...
REVISR - Git Management for WordPress : keep track w/ version control
GitKraken - The intuitive, fast, and beautiful cross-platform Git client.