Animal Planet: Saying Goodbye
   How to face the biggest decision of all, when to end your cat's life.
   http://animal.discovery.com/guides/cats/catcare/goodbye.html

CatStuff: Helping Your Cat Deal with the Loss of a Companion
   Provides information on how to help your pet cope with the death of a companion animal.
   http://www.xmission.com/~emailbox/coping.htm