Like you, I can't quite imagine how awesome getting clothes could possibly get, from anybody. I've heard the return policy is very accommodating, maybe that's a major differentiator?
Also, customer service interactions can be so dehumanizing, I could see how anything even slightly pro-active would feel radical.
I've never bought anything from them, so I can't comment on how innovative their service is, but I've read enough from people who've toured their offices that I do believe their company culture is something unique (getting paid to quit if you're not drinking their koolaid after training, for example).
I'm always up for stories about emerging work-culture, and one thing about Zappos is that they're not a tech company. It's straight up consumer retail. I'm glad to hear "normal" companies might be rethinking how to create nice places to work that invest in their employees, not just tech startups.