Having a bit more of a think, how about Alien F1 (aka Virtual GP). It plays sort of OK on an 040/25, but is much better suited to 060.
Shadow Of The Third Moon uses a pretty decent voxel engine, but only lists 040/40 for max detail. I wonder how it plays with 060...
I remember a demo for a Mario64-style game. Can't remember what it was called, but if anyone knows and has played the demo with an 060 it would be interesting.