My roommate's cat tends to get fairly lonely I think—I assume that's why he yowls at us in the middle of the night. Perhaps getting him a talking water dish like the Chatterbowl would help. My roommate could record his voice with one of his usual sayings, like "No, Sox! No!"
The Chatterbowl takes recordings of up to ten seconds, which are then triggered when your pet takes a drink (by, I presume, a motion sensor). In fact, if you feel like leaving your cat a voice memo without having to have them resort to the waterdish, you can buy the Chatterbowl's mechanical heart, the TalkBox, for just $10. The Chatterbowl costs $20 on its own.
Of course, if your pet is deaf as a post—as I suspect my roommate's cat is—this isn't going to help that much. Then you have to resort to the tried-and-true cardboard cutout method.
[via Shiny Shiny ]