I kind of like the concept of having the product and the network do the marketing. Craigslist did not spend any money marketing but yet they were able to grow e

I kind of like the concept of having the product and the network do the marketing. Craigslist did not spend any money marketing but yet they were able to grow entirely based on their product/service. Any competitor could have stepped in and actually had a marketing campaign to steal the show but nothing happened. Similar to facebook I suppose.