Almost anything involving the space-magic Enterprise D dish between the engine nacels:
Need more power? Modify the main deflector and divert power from shields.
Space anomoly? Bombard it with tachyon particles from the main deflector.
Need to modulate frequency of phaser array because a borg cube adapted to your weapons? Use the main deflector to send a resonance pulse and overwhelm their shields with a flood of positronic particles.