Official websites:

BBC - Doctor Who
BBC - Sarah Jane Adventures
BBC - Torchwood

Doctor Who fan websites:

Bad Wolf TV

Children of TARDIS
Doctor Who Online

DWEB - Doctor Who Ebooks

Gallifrey Productions

Laser Screwdriver

Planet Gallifrey
Sylvester McCoy - The Unofficial Site

Ultimate Doctor Who
Tardis Travels
The Doctor Who Site
The Doctor Who TV
The Oncoming Storm

The Tardis Communicator
Toys - Doctor Who World
Will and Seb's Blog
Whoviavortex

Sarah Jane Adventures fansites:

DWF - Sarah Jane Adventures
Sarah Jane.TV

SJA Latest

Miscellaneous sites:

Action Figure Theatre
Dr Who Locations Guide
Dr Who Logo Collection
Rob's 3D Dr Who Images

Doctor Who spin-off sites:

Bad Wolf
British Rocket Group - Guinivere one
Cybus Fitness
Cybus Industries
Defending The Earth - Mickey's Site
Deffry Vale School
Electromatics
Geocomtex - Van Statten's Site
Martha Jones on Myspace
Torchwood (interactive game)
Torchwood House
Vote Saxon - Harold Saxon Site