Official websites:

Mary Jane Music (Marie's and Micke's label)
mariefredriksson.se (EMI's website)
Roxette
Son of a plumber
Per Gessle

Recommended Marie sites:

Worship Marie
Marie Fredriksson Online
LittleMarie.net
Unofficial Marie Fredriksson Site

Community:

MF forum @ Worship Marie
MF forum @ Marie Fredriksson Online
Run To Roxette Forum
Small Talk
SOAP.com Forum
Planet Roxette Forum (in German)