One of the latest website addition to the web is TripTouch , it will give you all the information on your destination city such as current weather, what's on, restaurants, local entertainment information, highlights of the city etc. You can even put up a public announcement of your arrival for the whole world to see when you will land.
Infoplease section on countries of the world has a great deal of detailed information regards each country. Others are Wikipedia and always a great source of information WikiTravel. Finally you cannot do better then Lonely Planet if you want geographic information as well as in depth city guides.
For city guides try TimeOut.
