I remember the Hampsterdance (unfortunately), All your Base are Belong, Dancing Baby and (that poor) Star Wars Kid as fads. Friendster and Blogger, and to some extent Jibjab, are commercial sites - some people made money off these ones. Mahir, Ellen Feiss and Hot or Not seem to have passed me by.
What am I talking about? The list of 'Top 10 Web Fads' on C-Net. Good for a few minutes distraction on a Monday morning before you put your head down.