GitSpo - Measure & engage your open-source community
Cheat Sheets Dev - Community built to share popular programming snippets.
Devo - Devo delivers real-time operational & business value from analytics on streaming and historical data to operations.
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.
Ruby Toolbox - Explore and compare open source Ruby libraries
GitSheet - A dead simple Git cheat sheet.