An online `socratic book' pedagogically describing the building of a N-body simulation code for stellar systems. Software (in Ruby) is included.

Cloudy is an extensive, well-established, large-scale spectral synthesis code designed to simulate fully physical conditions within an astronomical plasma and then predict the emitted spectrum. The web page contains links to papers published with cloudy, the most recent version of the software itself, and a discussion board.

CMBEASY is a C++ code with GUI for calculation of CMB power spectra and other density fluctuation evolution data for a given cosmology.