Zube - Project management for developers.
Refined GitHub - Browser extension that makes GitHub cleaner & more powerful
Matrify - Manage information in tables.
GitZip - Download or create a download link for a GitHub project folder/sub-folder or file.
Binary Tree - solve issues and manage documentation; no spreadsheets
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.