Refined GitHub - Browser extension that makes GitHub cleaner & more powerful
GitNews Web - Trending repositories from GitHub, HackerNews & Reddit
GitZip - Download or create a download link for a GitHub project folder/sub-folder or file.
LibHunt - LibHunt tracks mentions of software libraries on relevant social networks. Based on that data, you can find the most popular projects and their alternatives.
Zube - Project management for developers.
Ruby Toolbox - Explore and compare open source Ruby libraries