I'm not sure if I'd consider Facebook's model to be two-sided, at least their startup model. I'd consider two-sided markets to be businesses like eBay or Airbnb

I'm not sure if I'd consider Facebook's model to be two-sided, at least their startup model. I'd consider two-sided markets to be businesses like eBay or Airbnb. I remember reading something on Airbnb (it might have been a Mixergy interview) and one of the takeaways for building a two-sided market is to employ promotional tactics that are not scalable. If I remember correctly, Airbnb went to New York City and started knocking on doors to drum up listings. Obviously, such a sales tactic at scale would be extremely expensive and prohibitive, but when starting out, you need that level of intimacy to get off the ground. I believe the other example from that article was a babysitting service where the founder went around town and plastered fliers where appropriate.