scottbrit's comments

The granularity with which you can recognize trends and speak to exactly what your customers are looking for in copy is far enhanced by keeping a document like this than memory or mnemonics.

When Richard Branson was asked how to be more successful in business his response was - "Work out"

Aside from it being a great product, they have a ton of viral mechanics built in. The fact that you can't sign in unless you have a facebook friend on the service resulted in people broadcasting on across social platforms which generated lots of buzz. They also prominently display a ton of sharing functionality and let's be honest - people like sharing what music they're listening to