|Simulated low light photograph - notice the blurred pinwheel|
Camerasim is an online SLR simulator that allows you to experiment with a camera's settings and see how they impact the resulting photo.
Its viewfinder shows a scene of a little girl who's holding a spinning pinwheel and standing in front of some playground equipment. You start by setting the ambient light and your distance from her, then you can adjust focal length, ISO, aperture and shutter speed while referencing your light meter before snapping your picture to see the results.
The simulator also has brief explanations of the various terms used in photography and what the settings do. Try it out, maybe it will give you confidence to turn your digital camera's 'auto' setting off and fiddle with the controls a little.