when i got my first computer, i was in middle school and i got a yahoo email address. looking around yahoo, i found yahoo groups. there were and are groups about anything and everything. groups for crafting and books and everything in between. i'm pretty sure the first social networking thing i joined was yahoogroups. i don't remember the specific group, but even back then when i was around 12 or 13 yahoogroups looked clunky and ugly, the messages were through a messageboard format and people would send them through emails which also made the messages, well messy. i'm pretty sure i'm still in some yahoogroups, except i never check the messages through e-mail or at the group's page.
now i use twitter, facebook and flickr primarily for social networking and these sites are much more interesting to be around and way more dynamic with their ability to combine images, text, links outside of the site without being so messy with the email formatting.