Dateutils are a bunch of tools that revolve around fiddling with dates and times in the command line, with a strong focus on use cases that arise when dealing with large amounts of financial data. Their target market is shell scripts that need date calculations or calendar conversions, and as such they are highly pipe-able and modeled after their well-known cousins (e.g. dtest vs. test, or dgrep vs. grep).
Cdarts is a low level implementation of a computer darts player. It can be used as an opponent against a human in the game, or it can be used as a simulator for fun. It currently supports only two different game types (301 and 501), but can be extended to support more games. It supports three different levels: beginner, hobbyist, and professional. Each level tries to simulate a human at that level as well as possible.
libpetey is a small scientific/numerical computation library. It includes the following components: templated sorting routines; templated binary tree classes; a templated linked-list class; routines for finding the k-least and k-greatest elements in an array; "supernewton", a one-dimensional root-finding algorithm based on cubic interpolation; a class for working with dates and times; a function for easy parsing of command line options; datasets (the beginnings of a data-representation paradigm that generalizes matrices but is mainly useful for n-dimensional linear interpolation); and sparse matrix library including command-line utilities for sparse matrix multiplication and eigenvalue decomposition as well as a sparse matrix calculator.
POSIXplorer will help you find, navigate, and open files on Linux, Mac OS, or most POSIX systems. You just type the command and then a regex for which you'd like to search. By default, it searches filenames and excludes class and other data files. It looks recursively down from your current directory. If you'd like to search through file contents, use the '-c' flag. When using -c, after the regex, you can list a file pattern, such as * (the default) to match any file or *.java to match Java files. After searching on your query, it presents a list of results and lets you type a number to select one for opening in the editor you have defined in the EDITOR environment variable, or by default Vim. After quitting the editor, you come back to your results and can continue opening files or execute a new search. To run a new search, just type the query and the script will detect that you did not intend to enter a file number. Note that in content searches with -c, only a new content query can be entered, not a new file filter.