Computational Astrophysics
Links
N-Body/Particle Simulation Methods
http://www.amara.com/papers/nbody.html
An extensive online tutorial with examples and code references.
NEMO
http://bima.astro.umd.edu/nemo/
[open source - Unix] An extendible stellar dynamics toolbox; has various programs to create, integrate, analyze and visualize N-body and SPH-like systems. In addition there are various tools to operate on images, tables and orbits, including FITS files to export/import to/from other astronomical data reduction packages.
Aarseth's N-body software
http://www.ast.cam.ac.uk/~sverre/
[open source - multiplatform] Direct N-body algorithms.
Barnes & Hut Treecode Algorithm
http://www.ifa.hawaii.edu/~barnes/software.html
[open source - multiplatform] A guide to a tree code algorithm implementation, used for astronomical N-body simulations.
ORSA - Orbit Reconstruction, Simulation and Analysis
ORSA is a C++ framework for the development of algorithms and programs oriented to the simulation and analysis of the orbital evolution of bodies in space.