animating object's visibility, not material

Is there a way to animate visibility at an object level, rather than at a material level (so that I don’t have to have multiple variations of one material), and without using layer switching animation (I need a blend). I’ve never seen or read anything about this - anybody have any ideas? And without using the compositor…that’s just too much work for this project.

You are right, object level visibility would be done by layer animation, my only other suggestion would be to key the alpha of the object. and yes that would be at the material level. But you shouldn’t need several variations. Just 100 % alpha and 0 % alpha.

Unfortunately you have to do it thru Materials. Select one Object and in the IPO window add a new MatIpo with only one IPO for Alpha. Link that MatIpo to all the other Objects.