There's always the new science usage of the GPU for scientific computation.
The article Scientific computing on the GPU, which contains some interesting links, says:
The scientific distributed computing project, Folding@Home is seriously investing into this approach and claims to be able to obtain a performance of about 100 gigaflops from a standard desktop PC/Mac. Recall, that today a high-end desktop can deliver a few tens of gigaflops at most, using all the cores of its CPU. So, it's an order of magnitude improvement in performance!
See also this article : From CPU to GPU.
And remember that one PC can contain several GPUs, and that way be the equivalent of a large cluster.
