http://camera.beograd.com/
This camera is placed on Terazije, facing towards hotel Moskva. this one is "fixed", you can't control it. I believe that in a clear day you can even spot Hram Svetog Save at the far background :)
Now, the controlable cams!
http://www.informatika.com/webkamera/trg-nikole-pasica.htm
Trg Nikole Pašića: if you move this cam to the right you'll see the ice skating rink, which is always illuminated by colorful lights at night :)
http://www.informatika.com/webkamera/novi-beograd.htm
Novi Beograd: this cam shows a beautiful view of the new part of the city, specially at night, when the buildings are all lit up
http://www.informatika.com/webkamera/ada-ciganlija.htm
Ada Ciganlija: this cam is cooler during daytime and specially during summer, when the river island and its beaches are crowded with people.
Enjoy! :)
