Deck - A multi-timeline viewer for GitHub repository events
GitKraken - The intuitive, fast, and beautiful cross-platform Git client.
JXL for Jira - The power of Jira with the familiarity of spreadsheets
SourceTree - Mac and Windows client for Mercurial and Git.
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.
GitHub Desktop - GitHub Desktop is a seamless way to contribute to projects on GitHub and GitHub Enterprise.