The Panoramas.dk site has a large collection of panoramic photographs. I think the best of these is the one of Cologne Cathedral. It is a stunning application of the technique. Try looking up and down as well as around. You can also zoom in and out. You will need to have the free QuickTime plugin installed.
If you look at the photographs on the Panoramas site you can see some really good applications of panoramic photography. I particularly like this one of Red Square. Others do not really seem to work; either because the camera has been badly situated, or the subject is not really suitable for panoramic photography.