Thank you all for the helpful suggestions.  I've followed them ALL.  Spent
several more hours searching by car, posted REWARD signs at all the pet
shops as well as the nearby stores and traffic intersections, notified
everyone who can be notified, etc.  We scattered his litter around the
outside of the house and put his cage out so he could smell it.  Every kid
or jogger for miles has been accosted by me waving Thunder's picture at them
and I put up signs with his picture at the weekend garage sales in the area.
I've spent the last few nights sleeping fitfully by the open door with his
blanket.
 
Thanks for your advice and support, and keep us in your thoughts.
Scotty
[Posted in FML issue 1894]