Top 10 Web fads

1. Hampsterdance (1998)
2. Mahir (1999)
3. All your Base are Belong to Us (1998 – 2001)
4. Dancing Baby (1997)
5. Hot or Not (2000)
6. Friendster (2003)
7. Ellen Feiss (2002)
8. Star Wars Kid (2002)
9. Blogger (1999)
10. JibJab (2004)

Found here on CNet 

My top 5 fads of the future:
1. Face book
2. My Space
3. Windows live
4. Yahoo
5. Blogs/Wikies