I recently finished reading Kat Albrecht's The Lost Pet Chronicles: Adventures of A K-9 Cop Turned Pet Detective and it has some excellent ideas for finding a lost pet. Stetting traps- more than I could ever say here. I would advise you to call EVERY shelter/rescue and vet and go searching every minute of the day and certainly place a humane trap near your home with a videocam near it if possible. With your pet's fav food.
Her site is:
http://www.katalbrecht.com/
She works fulltime as a pet detective and there may be one near you (It is a growing field- one I;d love to do on the side actually if I had time but I am
lucky to SEE the weekend, lol) Granted, there is one now in Nova Scotia.
These sites also offer helpful tips:
http://www.pet-detective.com/
http://www.pmia.com/
http://missingpetpartnership.org/
Good luck!!!!