This is very cool. Although I don't know how accurate this is, if calibrated and tuned to yield a certain degree of accuracy it will have a variety of use cases.

For example -- When interviewing someone, being able to run their github username (if known of course) to analyze their commit messages, comments, discussions. Or even their hn, reddit, twitter user names (if the usernames are linked with their first names, nothing creepy). It will potentially help to identify candidates that are downright rude, arrogant etc.

Or analyze internal mailing lists, hipchat/slack channels for co workers who are potentially burnt out.