Computer/smartphone gadget source USBfever offers up this neat little wide angle lens for your iPhone. the US$16.99 lens comes with a screw-in mounting ring that adheres around your iPhone's camera lens, as well as front and back lens caps. (The lens also has a built-in magnet to stick right to your device's case, where applicable.)
USBfever suggests videoconferencing as the primary app for this lens, which should work on a variety of smart phones, PDA's, and even notebooks in addition to your 1G/3G iPhone. (Here, as everywhere, caveat emptor applies…) Need to go longer — or even wider? Check the bottom of the page for a variety of telephoto and fish-eye lenses.