Erin-related links:

official sites:
Erin's World (Esurance's site)
Ghostbot (animators' site)
Punch Pants (Ghostbot's blog; includes fanarts)

unofficial sites (blogs, fanarts, videos, etc.)
Bully Says: Comics Oughta Be Fun!: What the comic book industry needs
Cold, Hard Flash: Enter Erin's World
How Esurance Lost Its Mascot to the Internet
The Johnny Bacardi Show
Michael Prescott's Blog: Desperately seeking Erin
PushBox: Pimp My In(e)surance Company
Retro Junk | Return of Cartoon Love
TV Tropes
Uncle Andrew Dot Net You Can't Spell "Illustration" Without "Lust"
Uncyclopedia (mirror)