Links

Technical

Cropping
http://graphicssoft.about.com/od/photoshop/l/bllps502fx6.htm
http://www.mediacollege.com/graphics/photoshop/tool/crop.html

Framing
http://www.tutorialized.com/tutorial/Cropping-and-framing-in-photoshop/13755

Elements and Principles of Design

General
http://www.goshen.edu/art/ed/Compose.htm
http://www.princetonol.com/groups/iad/Files/elements2.htm
http://www.jiskha.com/art/visual_arts/ped.html
http://www.4h.uidaho.edu/programs/kidspace/E-P.htm
http://www.onlinephotography.com/design.html

Composition

Rule of thirds and cropping.
http://www.tutorialized.com/tutorial/Crop-with-Rule-of-Thirds/9670

Gallery