Registration Flow: What are some examples of great new-user experience flows on the web?

https://www.quora.com/Registration-Flow/What-are-some-examples-of-great-new-user-experience-flows-on-the-web

Quora is your best source for knowledge.Sign up in seconds. What sites offer the best new-user flow in the form of a tutorial/wizard/tour/step-by-step?