Official G-Shock and Casio Sites:

gshock.com – Official G-Shock USA site
gshock.co.uk – Official G-Shock U.K. site
gshock.ca – Official G-Shock Canada site
g-shock.sg – Official G-Shock Singapore site
g-shockaustralia.com – Official G-Shock Australia site
g-shock.eu – Official G-Shock Europe site
g-shock.jp – Official G-Shock Japan site
world.g-shock.com – Official G-Shock sites for other regions
baby-g.com – Official Baby-G USA site
Official Pro Trek USA Site
ProTrek.com – Other official Pro Trek sites

Official Casio Support:
Select Country or Region for Support

G-Shock Replacement Parts:

PacParts (USA)
American Perfit (USA)
Tiktox (UK)