Extremely High Resolution Image (2048 x 2048 -- 128 samples / pixel -- rendering time : real 279m22.153s, a bit over 4 hours)
This is the first image that I generated with spheres of different index of refraction, and ratio of reflectance to transmission. Overall, I think it looks pretty cool. There are a few minor changes I would like to make, but they shouldn't take too long. The sky needs to be changed from my polluted sky brown to a beautiful blue, the small middle sphere looks like it is getting clipped by the camera and the two upper spheres need more reflectance. This was still a ton of work getting here.
I like the color of the balls visible in this one
A box and a sphere
Messing with a transparent sphere and box
One of the passes at multiple spheres - after getting this far scene layout is taking a while
Index of refraction = 1.0, with some phong shading going on
Totally reflective - but still phong shaded
I also found an interesting blog by Pete Shirley, a professor at the University of Utah, about graphics. My professor, Joe Kniss, went to Utah and studied graphics. Check it out here. I also added him to the "friends links" that I support, even though we have never talked (so aren't friends).