Not sure if anyone uses this already
The Photographers EphemerisIts a neat little mashup based on Google earth that allows you to get exact sunrise and sunset times and angles for any location on the planet on any day
In this image on from their website
You can see the lines representing sun/moon rise/set on the map and the paths taken across time on the display on the right
Theres also an additional marker (marked 4 on the screen shot above) which you can drag out to your subject which allows you to work out apparent sunet/rise based upon differences in altitude
Sounds complicated but its pretty easy to use - and also available as a download for the iPhone