"We interview people for culture fit. We want people who are passionate about what Zappos is about--service. I don't care if they're passionate about shoes."
I'm not entirely sure how accurate that is. Perhaps I'm used to software--in which jobs aren't [hopefully!] excessively tedious--but I'm sure lots of us participate in non-work-related forums and mailing lists, helping others for free, just because we are passionate about the subject matter.