have you tried the fur mice with the shaky bits in?? mine get bored of the normal ones but the shaky ones catch their attention more x
also you can get a laser thing from petsathome that randomly throws a lightbeam around the room, thats quite a funny one lol xx
or door frame hanging squeaky mice are fun too

xx
or aswell hairbands

mine are forever going missing (usually under the washing machine which is lilly's fave hiding place for them lol x She fetches them back for you if you throw them though

) xx