Software you can download (and probably have to compile):

• AIPS++, Astronomical Information Processing System (1992-2003)
• Athena, astrophysical gas dynamics code. (2002-)
• ATM, Atmospheric Modeling (2000-)
• cmhog PPM code (1995-)
• COMB, single-dish radioastronomy spectral line data reduction (1986-)
• HNBody, Symplectic Integration Package (1999-)
• MIRIAD (1987-) [also: WIP, rad, Xcorf, checker]
• NEMO, stellar dynamics toolbox with N-body/Image/Table/Orbits (1986-)
• partiview (N-body visualization)
• RPLsh, arbitrary precision Reverse Polish calculator shell
• WASP, Wideband Analog Spectrometer software (1999-)
• WIP, PGPLOT based interactive Graphics Software Package
• ZEUS-MP, Parallel version of the ZEUS HD and MHD code.

Java based on-line tools:

• WITS, Web Infrared Tool Shed. (1998-)
• Astronomy Workshop
• JStatus BIMA array status applet
• GetHA: How To Determine A Sensitivity Based HA Range
• JRms BIMA Sensitivity Calculator

Other software related activities:

• CVS, source code revision system
• astromake, a poor-man's linux astronomy software collection
• Theory Virtual Observatory, collections of theory data for the future VO
• LMA software
• SBN-Developed Software Tools (FITS<->PDS, IDL)
• Astronomy Department Software
• Derek Richardson's archives contains some software: xa (X11 animation), boxtree (n-body code), roche lobe demo

Not so free software

• pkdgrav (n-body; U.W. group w/ D. Richardson)
• RHESSI software (needs IDL 5.3+)