Distributed-median is a project mainly written in JavaScript, it's free.
implementation of how to calculate the median of a distributed data set -- project homepage is a demo
During an interview, I was asked about how to implement a distributed algorithm that would calculate the median of a list of numbers distributed over multiple machines. No one machine can hold all of the data. This demo shows an "omniscient" supermachine that knows all the data on the left-hand side and simulated multiple machines on the right-hand side that implement the distributed median algorithm. I think it's a really good question.