Who spreads your word?

In order for an idea to spread, someone has to do the spreading.

In the dark ages (ten years ago), the only way to spread your idea on a large scale was to do it yourself. Lots and lots of ads.

Today, marketers get all sweaty thinking about how this happens magically, virally, for free. If it were only that easy.

What's interesting to me is that different products and ideas are spread by different groups of people. There isn't just one professional association of idea spreaders, with everyone else