iPhone Trick
I was having a lot of trouble using my iPhone. I could not get close to the phone while on a call. The phone display would be shut off by the sensor. This is a useful feature to keep the touch screen from acidently being pressed while holding the phone close to the head. I had to get close to see the address book or mail applications and every time I did I would be able to read the screen. I had to beat the sensor to get a peak.
I found a work around. When the earbuds are plugged in, the screen sensor will not shut off the display. So if I neeed an address while on a call, I plug in my ear phones. I would rather have a preference setting to turn the sensor on or off. Maybe in iPhone 3.0.