The Institute for Computational Science is developing and maintaining various software. These can be downloaded freely and documentation is available on the corresponding code sites.
PKDGRAV is the world fastest N body code. It uses the fast multipole method, and exploits the MPI library, together with multi-threading and GPGPU acceleration.
GRAFIC++ is an MPI-parallel cosmological initial condition generator, that can be used to generate multi-trillion Gaussian random field particle data sets.
SKID and Grasshopper are particle-based tools to identifiy density peaks in any N body data sets. It is used to detect bound structures and sub-structures in cosmological simulations.
RAMSES is a general purpose, massively parallel, grid-based N body and hydro code using the Adaptive Mesh Refinement technique. It features magneto-hydrodynamics, radiation transport and various galaxy formation physics modules.
GENGA is a GPU based, collisional N body code, used to study planitesimals dyanmics in the solar system.