Prebuilt Animatronics
Another way to go would be to "hack" an animatronic toy like "Furby" or those singing fish wall plaques. There are tutorials all over the net about it. However, unless you do some MAJOR electronics work you're going to be limited (in most cases) to the pre-recorded dialog/movements. You can still find new ways to activate it, but most of that stuff is "hard coded" in there.
Note: This also voids any warranty on said toy.