You might like John Walker's Earth viewer.
Earth View
This shows a "satellite" view of the earth with the sunlit and dark areas represented. By default it shows "now", but you can enter any time you like into the viewer and it displays the appropriate image. I am not sure of the images are actual photos or computer generated or some combination of the two. You can also enter a desired viewpoint.
Of course (well I just found it
Google Earth has a similar function. Use the "Show sunlight across the landscape" button.