I miss Myspace, it was way less creepy and IMHO led to much more meaningful communication.
The social network I miss is Mixi, which was a sort of proto-Facebook around in the early 2000s (in Japan and Japanese only). Mixi had some really interesting features like being able to see who had browsed your account. (To be fair Mixi still exists, but they kind of died when FB became popular, as well as putting itself out of business with some onerous changes to their terms of service and business practices.)