The World Press Photo organisation have archived a collection of images from the competitions beginning (WPP is a very prestigious awards body for photo journalism). Very little to do with wedding photography I know, but very powerful photography all the same. Even if this is not your thing, use the search funtion to find the overall winner for each year. There are some controversial images in there but certainly also an indication of the power of a single image. This is probably the best collection of this kind of work online:

http://www.archive.worldpressphoto.org/