The key lessons:

  1. Make the top 25% advocates gather and share the great stories.
  2. Do it on a site that sends people to the stories, not fence them in.

Lego Launches a New Social Media Platform http://www.wired.com/geekdad/2012/01/lego-rebrick/ by GeekDad @ Wired.com

See also: ROI of social media