Predicting the light: "The Photographer's Ephemeris" by Stephen Trainor
I just wanted to recommend a piece of handy new free software by landscapist, Stephen Trainor called "The Photographer's Ephemeris," which brings together a number of useful tools for predicting lighting for landscape and architectural photography in one package--
I haven't figured out all the advanced features for myself, but beyond the obvious things like figuring out when the golden hour is and the direction of the light at a given time of day, it will let you figure out things like when the sun will drop below a ridge line before sunset or for how long a rock face will be illuminated on a given day. To figure it out, I've got the location set at my apartment and the current time and date set, and I'm looking out the window and seeing what the software tells me about what should be where.
Of course on a cloudy day all bets are off, and planning landscape trips often depends more on when one can get away than where the light will be, and the best photos are often the ones you didn't plan, but it does seem useful for figuring out where the lighting conditions will be good in a general way, or for careful planning when you want to return to a place you've already photographed when the light is in a certain spot.