Photographer's Ephemeris App
If you frequently need to plan sunrise/sunset/moonrise shoots, this app for the iPhone and iPod Touch is excellent. And, yes, it's worth the $8.99. I have been using the free version on my laptop and find it to be incredibly helpful for planning.
No, I don't make any money if the app sells. I just think Stephen Trainor has developed a fantastic app for us outdoor shooters.