TOPCAT is an interactive graphical viewer and editor for tabular data. Its aim is to provide most of the facilities that astronomers need for analysis and manipulation of source catalogues and other tables, though it can be used for non-astronomical data as well. It understands a number of different astronomically important formats (including FITS and VOTable) and more formats can be added.

PortSentry has the ability to detect portscans(including stealth scans) on the network interfaces of your machine. Upon alarm it can block the attacker via hosts.deny, dropped route or firewall rule. It is part of the Abacus program suite.

You would use ncview to get a quick and easy, push-button look at your NetCDF files. You can view simple movies of the data, view along various dimensions, take a look at the actual data values, change color maps, invert the data and other simple visual operations.

xphoon sets the X root window to a picture of the moon in its current phase, including the partial lighting of the dark side by reflected earthlight. Picture is a monochrome dithered bitmap which is calculated via mathematical formulae. It keeps running on background updating the picture accordingly as time goes by.

Calibrates and characterizes display devices using a hardware sensor, driven by the open source color management system Argyll CMS. Supports multi-display setups and a variety of available settings like customizable whitepoint, luminance, black level, tone response curve as well as the creation of matrix and look-up-table ICC profiles with optional gamut mapping. Calibrations and profiles can be verified through measurements, and profiles can be installed to make them available to color management aware applications. Profile installation can utilize Argyll CMS, Oyranos and/or GNOME Color Manager if available, for flexible integration.

StarDict is a cross-platform international dictionary lookup program.