Sometimes the pages are written by 'official' bodies for the places in question; more often, they are written by people with a deep interest in the places concernted, or with particular pieces of knowledge or experience that they wish to share. The level of detail varies from pictures of everything in sight (which obviously makes the pages slower to download), video clips and soundbites, to text summaries with the occasional graphic to highlight a particular area.
For recommendations about places to visit, things to see, where to eat and where to stay in a particular location, the Web provides near-instant access to thousands of people's personal opinions on the subjects. They may not write in the polished prose of a professional guidebook, but their thoughts may well be more up-to-date and less fettered by the thought of possible legal action ...
A good example of a tour round a specific attraction is the Mary Rose Virtual Museum tour; it describes what you would see, were you actually walking through the museum, and it provides pictures and further information about the history and background of the famous ship. For those living outside the UK, it may be the closest they will come to Portsmouth!
Those fond of TV soap operas may also enjoy the Brookside Virtual Tour. Clicking on the houses shown on the map of the Close will give you a history of that house's present and past residents, and their doings.
To see what can be done for tourist information for a larger area, look at the Hong Kong Tourist Board's site. They provide a guide to places to visit on Hong Kong Island, as well as useful information about hotels, places to eat, and even an interactive tour planner which, given some information about your interests, will suggest the places and events that you should not miss.
Of course, if you're looking for somewhere to visit that's just that little further off the beaten track, I recommend the Virtual Tour of Siberia in Summer. Apparently the weather is quite nice; you can see pictures of Lake Baikal, the scenic delights of Novosibirsk station, and some Russians enjoying the beach at Akademgorodok.
Finally, a travel site which has won many awards is Philip Greenspun's "Travels with Samantha". Greenspun travelled around North America in 1993 with Samantha, his Macintosh computer. Photos, reminiscences and the people he met are all detailed in this fascinating site.
Mary Rose Virtual Museum Tour:
Brookside Virtual Tour:
Hong Kong Tourist Association:
Siberia in Summer:
Travels with Samantha: