TreeMark
NVIDIA's TreeMark is an OpenGL-benchmark that uses a very high polygon count. You've certainly heard of it, it's simply a scene with a tree that is very detailed. The camera moves around the tree close and then again away from it and a few fireflies are flying around it.
That's what it looks like:
That's the tree from far,
and here is a close-up. You can see how detailed it is.