Kitty! is an iPad app that shows off a highly detailed, 3D virtual cat that you can play with. It's not like a Tamaguchi pet though — you don't raise it — but it's pretty interactive and reacts to your touch.
I don't want a pet right now, it's inconvenient to my irresponsible lifestyle. I'm sure others are like me! Or they're allergic. Or they're something. There are reasons. So Kitty! fills in that soft spot, albeit virtually, by letting me imagine what it'd be like to have a cat. If you pet it, it meows happily. If you play with it, it'll be gleeful. If you poke and prod it though, the cat will get ANGRY. So I've been poking and prodding it ever since I downloaded it.