Relentless Inquiry

Ad in Silicon Valley regional newspapers (eg, the Sunnyvale Sun): classifieds@community-newspapers.com

Report lost or found pet, search (free, plus $5 for image post, phone numbers, notification, etc): http://www.tabbytracker.com/lost_add.php

Free service, very nice google-maps mashup, lets you pinpoint GPS coordinates for where you lost pet; doesn't seem very used yet, searching all of CA for found cats returned nothing. http://www.findthatpet.com/