c-algos is a collection of algorithms that I have implimented in C.
quicksort.c contains an implimention of the QuickSort sorting algorithm.
It is WIP, and is known to be a bit buggy.
Added 2012/04/01
countInversions.c contains an algorithm which counts the number of inversions in an array (basically, how sorted the array is).
Added 2012/03/28