I've adopted a somewhat "word of mouthy" approach to PR, meaning organic sharing, without any promise of direct compensation, is the best test of a product's index of osmosis. Those of high index advertise themselves, which means, in today's parlance, they go viral i.e. spread of their own accord.
Does this mean I'm arrogantly boasting that I'm a master of word-of-mouth PR? On the contrary, I'm more the message in a bottle type, tossing out as many messages in as many bottles as I might afford, but it's a finite effort, and each bottle, in and of itself, is a long shot. To extend the metaphor, nothing stops the ocean from tossing them right back on shore, for me to open them.
What is my "product" you ask? Where do you click to get the succulent dessert cookies or whatever? Do I sell Champaign? I'm thinking of the new pink-motif retailer I stumbled upon during the Hawthorne Street Fair yesterday. They sell little pastries and alcoholic drinks.