Use this tool to calculate Multi-Cache Geocaches. The tool will take x number of caches and permutate pathways that you could take, then shuffle those pathways and randomly generate systems of linear equations to work your way through the cache. Error checking is limited at this point, so if you say you're using two caches and you don't put the coordinates in for cache 2, it just won't work out for you.
My wish list includes options for other functions, not just systems of linear equations. It would also be nice to limit the number of coordinates pairs you see based on your answer to the number of caches available, but that's just aesthetic. Finally, optimizing the code with permutation functions or recursion rather than nested for loops that are terribly inefficient.