I've recently started using a great free tool which helps a lot with planning landscape photography trips. It works out sunrise / sunset angle of view for anywhere in the world using google maps and allows the user to see the position of the sun for any location at any time of the year. Really handy.
My word, this is great. I have actually been playing with the math to do a much lesser program myself. (I only wanted a list of the day and times the sun pasted a particular point in the sky). This program is graphical and has many uses.