When you are planning outdoor photography in natural light, e.g. landscape and urban sceneries, a sun and moon calculator is a helpful tool.
I found an interesting application "The Photographer's Ephemeris" which can show sun and moon positions on a Google map and that provides also information about sunrise and sunset, moonrise and moonset and the begin and ending of the dawn.
The basic usage is fairly easy. One chooses a place, sets a date and with the slider at the bottom one can adjust the time, so that the lines for the current sun and moon positions are adjusted properly. In the example above the pin is located on an outlook point in the Rhine gorge and date and time are choosen that the sun goes down over the Castle on the other Rhine bank.
The application comes in three flavors: a desktop browser web app, an Android and an iOS mobile app. Here are links for