1. Shaolin Temple - it rebuilt the modern Shaolin Temple and redefined the martial arts, not only in the movies, but in the world.
2. OUATIC2 - it added a new gesture, beggar's hand, to the vocabulary of martial arts poses (OK, well maybe that was OUATIC1 but for some reason, I like 2 better.)
3. Hero - I've only since this twice (the other's I've seen dozens of times) but it's quickly becoming one of my all time favorites. The philosophical message is dead on.