I was introduced to a Chrome extension yesterday by Kenneth Kalmer that's completely changed my Github experience. Introducing Octotree, a sidebar for Github that shows a repository's code in a tree structure.
Take a look-see
I'd call that pretty rad!
You can download the extension by going to Octotree on the Chrome Web Store
After that, just browse to a Github repository and hit Ctrl+B or Cmd+B and you're set! To browse private repositories you'll have to set up an API token. Instructions will show up in the sidebar when you're browsing a private repo.