EPANETL is a localized (translated) version of EPANET, a popular hydraulic analysis program which can be used to simulate water supply networks.
Inptools provides means to convert and reproject files in the EPANET INP format. It includes the shp2inp, inp2shp, epanet2csv, and inpproj commands. (EPANET is water supply network analysis software.)
A game which looks like a Rubik's Cube, but is a slider, not a twister.
A fast C++ matrix library with an API similar to Matlab's.