Do you like photography ?
do you have a DSLR ?
do you have an iPhone ?
if your answer is yes to all, you should try to take a photo with your iPhone plus your DSLR Lens.
next question, how to do that ?
simple you just buy a case-adapter to mount your Canon EOS or Nikon SLR lenses to your iPhone 4.
with this adpater your iphone change to a powerful depth of field and manual focus camera.