When I joined Facebook, maybe that was about 3 or 4 years ago, there were only two from our large family who were signed up. As I was promoting several sites I was working on then, I invited close to a hundred to sign up. No one signed up - I'm quite sure of that. Back then, the applications were not as interesting. That could have been the reason. Poke was one but did not get many interested. Same with Friends for Sale. The only reason I was visiting FaceBook at least once a week or less was because of articles I was posting at Helium. I was getting good traffic from FaceBook as my Helium articles were automatically linked there.
During that time, family and friends were more on Multiply.com. Multiply did not have applications like FaceBook but it was a convenient social site getting updated with one another. However, just this 2009, many of family and friends are already signed-up with FaceBook because of interaction on several applications. The chat helps a lot in communicating with friends and family. It is also there where I was able communicate again with schoolmates from way back grade school and high school! Friend suggestions contributed largely on finding friends and even relatives that were unknown to me. FaceBook became more popular when it was featured on Discovery Channel as one of the big successes on the internet along with Google.