Commit Together by Github - Now add co-authors to your commits
Sortd - Rated the #1 App for Gmail
GitHub Marketplace - Tools to build on and improve your workflow
KanbanMail - A Kanban board for your emails.
Refined GitHub - Browser extension that makes GitHub cleaner & more powerful
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.