keeping objects upright in world space

I would like to keep certain objects upright (or another orientation) in world space at certain times.

LookAt(target, Vector3.up);

is perfect for the camera, but these objects won't be looking at any object in particular. They will have a position and direction determined, but the orientation is taxing to calculate sometimes, it would be much easier to have a function such as:

SetUpDirection(direction);

and the object would orient itself right way up with respect to direction, just how LookAt() does it.

Sorry if this has been asked before, thanks for help =)