Supports private repositories via Chrome Extensions > Follow for Github > Options
This extension will change the View button into Left and Right buttons on Github.com file diffs moves/renames.
Clicking the Left button will move you to the full file as it existed in its previous location in the parent commit. Clicking the Right button does what the old View button did, and moves you to the full file on the current commit.
Open source! See/contribute to the source at http://github.com/staff0rd/github-follow-extension