Erin-related links:

official sites:
Erin's facebook
Erin's MySpace
Erin's World (Esurance's site)
Ghostbot (animators' site)
Punch Pants (Ghostbot's blog; includes fanarts)
Wild Brain (um... other animators' site, I guess)

unofficial sites (blogs, fanarts, videos, etc.)
Adjab - The many faces of Erin Esurance
Art Of Andrew
Bully Says: Comics Oughta Be Fun!: What the comic book industry needs
Cold, Hard Flash: Enter Erin's World
Erin Esurance Videos
ian_j: Erin Esurance
I WANT TO EAT A NUT OF LAERMA! _
The Johnny Bacardi Show
Michael Prescott's Blog: Desperately seeking Erin
PushBox: Pimp My In(e)surance Company
ReadMe!Girls! (this seems to be Japanese)
Retro Junk | Return of Cartoon Love
Uncle Andrew Dot Net » You Can't Spell "Illustration" Without "Lust"
Uncyclopedia

Best Insurance Plan Ever (nude/sex animated fanart at ytmnd)