The two main uses of tilt/shift manipulation are to eliminate converging lines in architectural/product photography and to control depth of field issues.
AFAIK, there is no realistic way to accomplish this (without a TSE lens or a view camera) because the lens is always parallel to the imaging surface - be it film or a digital sensor. Doesn't matter if you tilt up or down or pan left or right, you are still using the same portion of the optic circle with all points being equally distant from the film plane.
Even using Photoshop to approximate this, there are distortions and resolution issues that do not occur when you actually tilt/shift the lens plane and image plane. And let's not forget rise and twist as they are normally used in combination with the other adjustments. It really is amazing what can be done when you have this level of control!
