In Batman: Arkham City for the PC, PS3, and Xbox 360, you can quickfire the Batarang during combos to increase your combo points.
To quickfire the Batarang, you simply tap the aim button quickly instead of holding it like you normally would.
On the Xbox 360, you tap Left Trigger to quickfire the Batarang.
On the PS3, you tap L1 to quickfire the Batarang.
