Photojojo, the people who bring weird and wonderful photography related items to our attention, are now selling a 3-in-1 iPhone 4/4s Lens Dial. The dial features a Fisheye, Wide Angle and Telephoto lens all of which are made from optical-quality coated glass. The housing is made from aluminium and it features two tripod mounts for portrait or landscape shots. To switch between lenses, you just rotate the disc as you do with the Holga iPhone Lens Filter Kit.
It's an interesting concept but at $249.00 (approximately £160.00) it's probably more sensible to put the money towards a DSLR or Compact camera.