I just found a nifty app for the iPhone called sun seeker ... Useful for finding out the direction in which the sun will rise.
It calculates the Solar Path for your current location and shows it on the display with hourly intervals. It also has an augmented reality view. You need an iPhone 3GS or iPhone 4 for this view. U could use this in an unfamiliar area the day before to determine a good vantage point for setting up for sunrise shots.
Any others apps (on iPhone, android as appropriate) for this? Are they any good?