Refined GitHub - Browser extension that makes GitHub cleaner & more powerful
Rainglow Color Themes - 320+ color themes for a variety of editors and software.
GitZip - Download or create a download link for a GitHub project folder/sub-folder or file.
Sweet Themes - Color Themes for Slack
Zube - Project management for developers.
GitLab - Create, review and deploy code together with GitLab open source git repo management software | GitLab