I had the pleasure of listening to theDuct Tape Marketing Podcast recently, the March 23 episode featureing David Meerman Scott, who recently wrote the book called World Wide Rave.  David makes some really interesting points about how trends get started on the Internet.  He provides numerous case studies on viral videos and blog posts, and how people have used these to build their businesses. 

Examples included Blendtec, a maker of heavy-duty blenders who increased sales tenfold after creating some wacky videos and the site Will it Blend?, showing their blenders chop non-food items.  He also talks about  Helaine Smith, DMD, a Boston Dentist who quintupled her business after publishing a free e-book called "Healthy Mouth, Healthy Sex."