The Acratech Panoramic head is a pan-tilt head designed specifically for taking panoramic images.  Despite the name, there is no technical or practical reason why the Acratech Panoramic can’t be used as a normal pan-tilt device.  In fact, as of this writing the Acratech is by far the stiffest, and incidentally also the lightest, pan tilt device I have tested.  There is just one catch.  The Panoramic doesn’t have a third axis of motion to level the camera out.