The Cat Dancer is a classic cat toy, and you can't beat the price ($2.75 on catdancer.com), but after a while, your triceps start to ache; I ended up attaching mine to a deadbolt. If you'd like cat toys that play with the cat for you, and/or let your cat do his pouncer-cise routine even when you're not home, I've got you covered.
But let's start first with another classic, the laser pointer. Cats looooove these, and you can get one in the shape of a mouse that doubles as a keychain ($10.75 on Amazon). Or you can get the slimline style with the attachment that makes the laser dot itself into the shape of a mouse (Drs. Foster and Smith, $8.99).
You still have to hold the pointer and press the button, though, so if you really want to automate, try the Laser Image Chase Toy from Hammacher Schlemmer ($29.95). Your dog might like it too; the laser oscillates in a random pattern and has four speed settings, as well as modules of 5, 10, 15, and 20 minutes of play.
The more analog version, the While You're Away Cat Toy ($39.95), is a motorized "teaser" (a feather/bell ball) that you can set to "Play While You Are Away" mode: the toy turns itself on for two additional 10-minute sessions, with a two-hour "rest period" in between (it chirps to alert the cat that it's about to start playing). Just suction-cup the WYACT to any flat surface and let the teaser dangle.
(The over-the-doorknob version, the Fling-ama-String Cat Toy from Acorn, is $34.95 and runs continuously for several hours...but is kind of a loud orange, which may not match your decor.)
