I’m in the process of implementing a coherent raytracer à la Wald (in parallel with Jacco Bikker) and getting programmer’s art to a whole new level of uglyness at the same time.
To give an idea here’s a rendition of Topa’s Turret Room, 122k triangles, 3 lights (specular + shadows, no texture) and a dozen materials on my 2Ghz k8:
http://ompf.org/ray/wip/20050224-01-3lights.jpg
But i'm really having a hard time finding detailed indoor scenes.
In fact this one is among the largest i've found (with an interesting/tricky-to-render design).
I could really use some help from a modeler.
So if you have such a large scene (a million or more triangles isn’t a problem) taking dust on your harddrive, please make a modelling impaired programmer happy 
PS: that raytracer will be open sourced at some point.
PPS: you'll find even more crappy screenshots [here](http://ompf.org/spgm/index.php?spgmGal=wip).