Github Punchcard WebExtension
Chrome Web Store
https://chrome.google.com/webstore/detail/github-punchcard/bpbennifjflmjcnoofbeaoiffphdbbad
Add-ons for Firefox
https://addons.mozilla.org/en-US/firefox/addon/github-punchcard/
Build from source
./build.sh
Background Story
http://openmymind.net/How-Meaningful-Do-You-Find-Github-Punchard/
https://www.reddit.com/r/github/comments/768oqr/is_the_punchcard_graph_gone_now/
https://github.com/blog/1093-introducing-the-new-github-graphs
https://github.com/guanqun/git-punchcard-plot