Jarv's scripts for analysis of Gaussian, VASP, and other calculations, horribly intermixed with highly site-specific files from the Imperial College London HPC CX1 cluster, and other computing resources.
I sulk when I don't have these files in ~/bin on a machine I'm trying to do scientific work on. Documentation is either absent or absently written. These scripts were often written for a specific problem, and then grudgingly reused.
Also see https://github.com/jarvist/hpc-bin/wiki for a slowly increasing Wiki of information on how to get stuff done.