In a brilliant wave of viral marketing, the BBC set-up a series of websites to tie into the Dr. Who universe.
Some of the sites were used in the show itself, such as in the premiere episode of the 2005 series, Rose Tyler used a fictitious search engine called search-wise.net, which is set up for film and TV productions to use instead of a real engines. Faux military sites like www.unit.org.uk have password access areas, giving some background and depth to the organization from the series.
Sites like www.torchwood.org.uk, representing the Torchwood Institute, currently contain little information. There should be more information there when the Doctor Who spin-off series, "Torchwood", starts in the UK on October 22nd. The CBC premiere date is unknown by me at this time.
In producer James Goss's words, these dozens of inter-related sites are "the most ambitious online fictional world ever." This may be a bit of an overstatement, as the Lost collection of websites is extensive, and also makes use of services such as Myspace, Flickr, blogs and podcasts to make the viewer feel as a participant.
The complete known list of Doctor Who sites can be found here:
For comparison, the complete known list of Official Lost sites can be found here:
Dr. Who, Doctor Who, Who is the Doctor, Lost, viral marketing