Cactus is a general, modular, parallel environment for solving systems of partial differential equations. The code has been developed over many years by a large international collaboration of numerical relativity and computational science research groups and can be used to provide a portable platform for solving any system of partial differential equations.
AstroAviBrowser is a small tool for astronomy imaging capture/processing. It allows you to open a video file, select the good frames, and save the new sequence in a new avi file using raw or lossless codecs. You may also de-bayer your frames and separate RGB plans. It's a kind of "AviRaw" for Linux.
Qastrocam is a capture program that can work with any video4linux device. Its main purpose is to do astrophotography. It can control a telescope to do guiding with the images received from the video device. It can also control the extended features of a webcam modified to do long exposure (several seconds) captures.
Astronomy for fun (education, science, whatever). Nightfall is an interactive application to simulate eclipsing binary stars, and to produce animated views, synthetic lightcurves and more. Takes into account the non-spherical shape of close binary stars, mutual reflection, and some other effects. Comes with documentation, on-line help, and lots of observational data of real binary stars. Supports the Gnome desktop, but doesn't require it.
INDI is an instrument-neutral distributed interface control protocol that aims to provide backend driver support and automation for a wide range of astronomical devices (telescopes, focusers, CCDs, etc.). Current supported devices include many telescopes, CCDs, filter wheels, focusers, and video cams. INDI is used in popular astronomy suites like Xephem, KStars, DCD, and Cartes Du Ciel.
Planets is a fun, interactive program for many-body gravity simulations. The emphasis is on play: it's easy to add in planets, zoom in and out, change the physical constants, save and load configurations, etc. It's designed to be easy enough for a kid to enjoy, but that hardly precludes adults.
GCX provides a complete set of data-reduction functions for CCD photometry, with frame WCS fitting, automatic target identification, aperture photometry of target and standard stars, single-frame ensemble photometry data reduction, multi-frame color coefficient fitting, extinction coefficient fitting, and all-sky photometry. It also controls CCD cameras and telescopes, and implements automatic observation scripting. Cameras are controlled through a hardware-specific server, to which gcx connects through a TCP socket. The program can control telescopes which use the LX200 protocol, and refine pointing by matching images to the GSC catalog position of stars. It generates FITS files with comprehensive header information.
pscal is a simple shell script that creates PostScript calendars. It's not the most advanced calendar creator available, but for quick, nice looking calendars, it's very handy to have sitting in your bin directory. Features include: font selection, user-defined holidays, phase of moon, and days past/remaining in the year.