Types of Images:

Symmetrical:

http://www.flickr.com/photos/naza1715/4120493736/

Assymetrical:

http://www.artistsnetwork.com/the-artists-magazine/striking-a-balance

Radial:

http://ecommunity.pwsd76.ab.ca/mod/book/view.php?id=32520&chapterid=5814

Golden mean:

http://briankshepard.com/

Rule of Thirds:

http://www.desktop-documentaries.com/rule-of-thirds.html