Apparently not everybody is pleased with the lens on the camera phone, even the 5-megapixel lens on iPhone 4. So a detachable lens as a complement is very necessary such as the Zeiss fisheye, macro and wide angle lenses.
For different purposes, this set of Zeiss lenses consists of one fisheye lens and one combo macro/wide angle lens. Each Zeiss lens comes with a detachable magnetic ring that allows you to fix the portable lens on the phone lens. The wide angle lens features 0.67x angle and 10-23mm focusing distance, and the fisheye lens features 180 degree angle.
The set of portable Zeiss lenses is priced at $40 USD. Of course, you also can purchase one of them separately. If you want one, jump to Photojojo for more details.