I'm working on a Haskell library for approximation algorithms.  In particular, I'm working on Partition, Knapsack, Vertex Cover, and possibly a few others.  Of course, I'd like to benchmark my library against other libraries in terms of both speed and the goodness of the solution.  So, are there any good benchmarks for these problems out there?  I'm looking for something like the UCI machine learning repository, but for approximation algorithms.
Benchmarks for approximation algorithms
reference request;approximation algorithms;optimization