I found this article by Landscape painter Johannes Vloothuis while looking for good discussions on composition. I found it VERY interesting, with excellent examples to illustrate some of the "rules." Some of the concepts will be familiar to photographers; however some of the concepts will cause you to think about how you are presenting your photographs today. Many of the techniques discussed in this article revolve around REMOVING detail and reducing contrast in peripheral areas of the picture in order to focus the viewers attention on the center of interest. This is an area where I could learn a thing or two. Perhaps I shouldn't be so concerned about extreme depth of field in my grand scenics, and should let the background blur out more often as Johannes advocates in his article.
Here's the link: http://www.wetcanvas.com/Articles2/135/120/
I'd be interested in hearing your thoughts.