Master & commander - good demo, boring film though
The Fifth Element - great video & Audio quality, excellent film and top totty too
T2 for the blue feel of the video and excellent THX soundtrack
Underworld - Great film for checking your grey scale at the beginning - Oh, and Kate Beckinsales outfit for black levels...
Ridley Scott for Cinematography - Gladiator for the video and film. Black Hawk Down for the gritty video and loads of helicopters.