WDIST (Weighted DISTance calculator) tool supporting the BGI Cognitive Genomics Lab's data analysis pipeline, and designed to grow into a full-scale replacement for PLINK (eta early 2014).  Since it uses streaming algorithms instead of keeping the entire dataset in memory, it can handle much larger files without the need for e.g. tedious chromosome splitting.  It also incorporates numerous micro- (and a few macro-) optimizations which collectively speed up most of PLINK's slowest functions by factors exceeding 100x (and sometimes even exceeding 1000x).