SunCalc is a great Google Maps based tool for finding the position of the sun and the sunrise and sunset times for any location on the Earth. The application auto-detects your current location but you also can drag the marker or use the search function to move to a different location.
A really great feature on this app is the time of day slider. The slider lets you view the position of the sun for any time during the day. You can even change the date to see the sun's position at different times of the year.
I can see this map being very useful for photographers, who may want to know the sun's position at different locations and at different times of the day. I also think this is a great tool for house buyers, who can check out when gardens and different rooms in a house will get direct sunlight.