As someone pointed out earlier the Canon 40D has the live view feature and it seems like more and more new dslr cameras are presented with a similar function. But I really think that the zigview solution probably is the best if photographing in crowded areas is a crucial part of your work. Holding a camera over your head and trying to see what is happening on the lcd is not an easy task anyway. The best solution would probably be to put the camera on a monopod and have the zigview display/trigger mounted further down. In this way it would work as a camera and periscope. But good light and short exposures are probably needed since there probably will be a lot of shake.