GitHub Reader - A quick way to browse GitHub issues and pull requests.
CodeTriage - Help out your favorite open source projects and become a better developer while doing it.
Shrink for Github - A macOS app for your Github issues
24 Pull Requests - 24 Pull Requests is a little project to promote open source collaboration during December.
Codetree - You can manage your entire development process through GitHub.
Gitpay - Add bounties to solve Git issues from projects.