I've had the opportunity to work in the production of various social networks. To see the real-time reactions from your users to your work is something exciting. Not all projects have been successful, sometimes things don't go as planned. But everything is useful to learn what users expect to find... and improved my skills.
One of my biggest project was the creation of a social network for a major international bank. I planned everything perfectly, every single detail was measured. The presentation was great, and everyone was delighted. But the customer underestimated the effort needed for the project and hired a cheap company without the knowledge necessary for its development.
What I learned from this? Well, while I was right on the way to explain the idea, I failed to make them understand how it should be done properly. Next time I will try to put more emphasis on the technical requirements...
Of course, not everything has failed. I created some social networks that have been very successful. Doblecero for "El Corte Inglés" or the social network of Calvo have been very popular, and I helped to increase positive customer perception of the brand.
Other projects for Nestlé, Hipercor or Cruzcampo had some gamification and socialization behaviours that contributed to the success of the campaign.