A standard reference on vertex sorting is:
Hoppe, H. 1999. Optimization of mesh locality for transparent vertex caching. In Proceedings of the 26th Annual Conference on Computer Graphics and interactive Techniques International Conference on Computer Graphics and Interactive Techniques. ACM Press/Addison-Wesley Publishing Co., New York, NY, 269-276. DOI=http://doi.acm.org/10.1145/311535.311565
There's an NVIDIA tool at:
One can do a bit better in terms of optimal cache hit ratio, but the tool works pretty well and has a variety of useful options.