I have always liked using window light as a main source of illumination. It is soft, natural, and very flattering in many situations. Instead of destroying the appropriate highlights and shadows with flash, when you use ambient window light you retain the correct relationship between light and dark in the picture. I've used it for many types of subjects, including portraits, art objects, architecture and product shots.

Using the light coming in from a window usually requires a faster ISO to compensate for darker conditions and it often means using a tripod.

Showing Motion: Flash-Blur
This is done by combining the flash with a long exposure. The result actually looks like a double exposure because the flash gives you a sharp rendition of the subject while the slow shutter speed results in a blur.

I find that dancers are among the best subjects to shoot because of the colorful costumes and artistic movements of their bodies. But you can also photograph athletes in motion, race cars at night, flowers blowing in the wind in low light, horses running and many other things.

The best circumstance for flash-blur photography is in low light conditions: indoors on stage, outside under a thick cloud cover, or at night.

Dramatic Natural Light
Let me explain why early morning and late afternoon light are so effective in producing exquisite photos.:

First, the color of the light is golden yellow, and when it bathes landscapes, architecture, wildlife, and people in its warmth the resulting images are transformed into works of art.

Second, the low-angled direction from which the light comes creates texture. Whether you are shooting a model or sand dunes, the definition of your subject is enhanced.

Third, the contrast between shadows and highlights is diminished so you can expose correctly for both.