Apple shot a series of aerial videos over New York, San Francisco, Hawaii, China, and London for its Apple TV screensaver, with astounding results. If you want that on your Mac, an open source project now lets you achieve that. Hit the source for the download and instructions.
Unfortunately, there is no day/night cycle support (so you only see day versions in the day, and night versions at night). Redditor InkognitoV says it doesn't seem to support it right now, but he "may fork the project and try to add this feature" if he can find the time.