The photographer's ephemeris (TPE).
The blog articles explain how to use it for photography planning.
But it's not strictly photographic software, so I thought I'd post it here in Viewfinder.
I used it to see if it's too late in the year to retake the late road home sunset shot with the E-P1 and it appears so. Sunset angle is too far south.
But since it wasn't direct sunlight straight down the road but at an angle, I think it may just be possible.