Oh, yeah, and waves in the water of those hyper-detailed Italian 16th century paintings, or tree leaves -- when lit correctly, you get specular highlights that seriously look like sunlight glistening on there. Blows me away every time.

Those paintings are quite low-resolution on average, but it took me a while to figure out how they could add so much resolution where it mattered, and turns out it's because they have an entire extra dimension to vary things in.