I was thinking about this for quite some time now. Finally, i made up my mind to make a macro lens extension and have those photos look more pleasing. The basic items required are lens (- the one used below is 25mm diameter), a 3.5mm audio jack, epoxy putty and Nexus one of course.
First, find a lens with a holder or a ring around it. I chose to break away the lens from a mini binoculars.
Fix the audio jack to the phone and hold the lens to its likely position. Mix the epoxy putty and shape it to hold the lens on to the audio jack.
Important:Put the phone to silent mode (or reduce Ringer volume to zero). The phone tries to send the tones of the shutter snap through the audio jack which is actually not connected to audio output device.
Why not use an Auto-focus lens and send signals via audio jack to control focus manually?