As Paul has ratified, I think it's more the rise of the Content Management System (aka blog software), and not Facebook/MySpace (although MySpace is considerably more CMSy than FB) that has signaled the demise of Geocities. Back in the day, if you wanted a web page, you had to hack it out in HTML and then FTP it somewhere.

Nowadays, anyone who still hacks it out knows exactly how sh1tty Geocities is.