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.
SetiContainer is a C++ class that allows convenient access to all the information in the state files of a SETI@home client. It periodically examines these files and updates its own data members accordingly. Other programs can use this class to extract information about the progress of the client, the found signals, or the work unit being processed. Additional functions offer more advanced info (like the amount of TeraFlops in a work unit, estimated time of completion, etc.). The SetiContainer class is based on the Qt toolkit, and extensively uses Qt's Signal/Slot technique.
x10ephem computes sunrise and sunset times. It consists of a library and an assortment of utilities. The most useful utility is x10events, which parses crontab files and updates the time fields to track sun events. Combined with an X10 interface like HEYU or X10, this allows the scheduling of lighting events to follow the changing seasons and daylight savings time automatically. This application does not depend on X10; it can be used for any crontab entry you like.
Xplanet was inspired by Xearth, which renders an image of the earth into the X root window. All of the major planets and most satellites can be drawn, similar to JPL's Solar System Simulator. A number of different map projections are also supported, including azimuthal, Mercator, Mollweide, orthographic, and rectangular.