Two examples:

Company A — a startup.  Builds a nice website with a strong value proposition and launches email blasts and telemarketing.  Using Google Analytics, we see very little traffic and slow growth.  After six months, I dismiss my partner.

Company B — a single person with almost no money.  Builds a nice website and writes a killer white paper on a key business topic.  Adds a case study and a podcast.  Zero outbound marketing.  No cold calls and no email blasts.

Which company does better?  As you might guess, Company B blows Company A away.  Hits are in the hundred in the first week and page views are almost 1,100.  Time on the site is two minutes even.  77.2% are new viewers.  And it is early.

Inbound marketing works.  Attract customers with great content. Use social networks to get the word out.  It flat out works!