Since we're touching code reviews, I'll plug my userscript here. It's useful for me for code reviews of big commits: you can fold the files, mark them as reviewed etc. and all of this is persisted in the local storage. You can install it from [1] if you know userscripts or read [2] otherwise.

[1] http://userscripts.org/scripts/show/153049

[2] https://github.com/jakub-g/gh-code-review-assistant