Off-camera flash rocks. And all your camera have the ability to take the flash off camera. On a Nikon, or a Cano 60D or 7D, you can use the pop-up fl;ash to drive the external flash. On other Canon cameras you need to use a 580EX flash or an IR controller on the camera.
And here, to motivate you, I shall show you another example or two, all take on Halloween night during a class at Sheridan College:
First, lit from below with a dual-color gelled flash:
Lit from below, suitable from Halloween:
The following photo actually uses one flash on camera, but aimed behind me. Note how I made the image B/W and added grain to give this photo a stark feeling:
Now a direct flash from our left:
Yes, even direct hard flash is usable, as long as the flash is not in line with the lens!
And here the same but with a grid on the flash, in case you want to avoid hitting the wall with light. (as a side effect, the grid also serves to slightly soften the light):
As you see, you can do a lot with a simple flash off camera.