As Facebook enjoys its moment in the sun, we should take a moment to step back and look at the history of computers and social communication. Some historical perspective is in order, both to assess the real value of social networks as businesses, and to anticipate how they are likely to evolve in the future.
Bulletin Boards

People have been using computers for social communication since the very beginning of the personal computer industry. Long before the Internet became accessible to the general public, people were hosting BBS systems, many of them focused on an interest group or local community. One particularly prescient invention was FidoNet, a network for BBSes that allowed systems to transfer data (messages, files, etc.) in bucket-brigade fashion to sites around the world. It grew to, at one point, cover much of the world, and was an entirely community-based effort.

Since not everyone had a computer , the communities that emerged in the BBS world largely revolved around computers in some way. Some BBSes focused on DIY computer projects, others on games, and more than a few were devoted to pirating commercial software.

Online Services

Web 1.0

Friendster

The Future

Profiles

Search (and the Social Graph)

Updates

Follow The Money

This list has been severely abridged. To read the full list and full descriptions, view the original post at it’s source:
Social Networks, from the 80s to the 00s (GigaOM)