On line classes in general, lack some important values found in a proper classroom setting. There are some resources that will add value to your photo skills, but actual classes can be more frustrating than anything else.
Interaction with fellow students, on site, on time assistance from instructors and seeing how others interpret the same assignment (ten or twenty other right ways to complete the same assignment).
Many times when you just don't feel like working, the energy of those around you can kick-start your creative energy ... sitting in front of a computer is usually not something photographers want to do. The people who like to do that become digital image retouchers, post production wizards and pre-press techs.
Resources:
http://photoinf.com/General/Robert_Berdan/Composition_and_the_Elements_of_Visual_Design.htm
http://www.kenrockwell.com/tech.htm
http://digital-photography-school.com/