Flac-utils is a toolkit for managing FLAC files. Its primary usage is syncing metadata between sets of FLAC files. Flac-utils also provides a Python module called flac_compare that can be used separately. The utilitiy consist of three tools: flac-sync, which syncs a file tree of FLAC comments for files with the same audio-part; flac-diff, which compares two FLAC files' metadata information and shows the differences; and flac-add-picture, which adds album cover art to the files using Amazon.
@ (monkey-tail) is a simple collection of simple commands. Built-in commands include listing of memory usage and open files for a process (by name or PID), running processes detached from a terminal, and running a program only once. @ can merge external pieces of code into itself to provide extra commands. Additionally, these "externals" can then be updated from their source. Currently there are externals available for extracting archive files (including nested archives), setting the GNOME desktop wallpaper image, and for replicating @ to another host via SSH. Externals can easily be written, as they are simply collections of Bash functions. It is completely self contained and self modifying, and is implemented in a single file.
Horology is a date/time calculator that supports all the built-in calendars for iOS, and allows you to perform various types of calculations or conversions of date and time values. You can find the difference between two date/time values, calculate a date/time by inputting a start date/time and add or subtract some arbitrary amount, or convert a value from one unit type to another (e.g., years to seconds).
gtk-screenshot is a program for taking screenshots. It captures the screen or a window and saves the image in the PNG format. It is similar to gnome-screenshot but it's not a GNOME application. All parameters may be specified on the command line, or the application can be graphicaly driven.
s6-portable-utils is a set of tiny general Unix utilities, often performing well-known tasks such as cut and grep, but optimized for simplicity and small size. They were designed for embedded systems and other constrained environments, but work everywhere. Other sets of small utilities are usually system-specific; for instance, the (otherwise excellent) BusyBox project only works on Linux.