Most of us have most often misplaced our phones somewhere nearby. And if you've ever put it on silent, it makes it harder to find your phone because there's no ringing to follow. Apartment Therapy has a neat trick that might help. Call the phone, and walk around your house with music playing.
The speakers on your music player may pick up the buzzing interference that happens when your phone communicates to the cell phone tower. When you get close to your phone, you should hear louder and more interference making it easier to track down the silent phone's location.