eCommerce is built on repeat customers.
Word of mouth really works online.
Don't compete on price.
Customer Service is an investment - not an expense!
All of these as well as the other lessons underscore one major theme: Customer Service. Zappos does their best to ensure they not only meet, they exceed customer expectations - so things like Encourage repeat business through awesome customer service. For example, Zappos will often automatically upgrade their customers to overnight shipping when they aren't expecting it, in order to exceed expectations and encourage customers to return to them.
Read all the slides at Zappos and let us know what you think.