If your hobby is photography, and you like taking photos with your iPhone you always carry, I believe Factron Simplex iPhone Case is designed exclusively for you.
Factron Simplex iPhone Case is not just a case protecting iPhone from damage, but also a practical attachment for adding various lenses to your iPhone. It fits iPhone 3G and latest iPhone 3GS, and is made of metal material. There is a little screw hole for additional lenses on the back of case matching the location of the iPhone lens.
Factron Simplex iPhone Case is priced at about $199.8 USD. Factron aso supplies compliant lenses, including a 40mm macro lens, a 25mm macro lens, a super wide angle lense, and two Fisheye lenses. Their prices are range from $19 to $60 USD.