selector is a command line utility for dynamic string selection. It reads the content of the specified files, and as the user types a list of strings separated by ";" (or a regexp), the display is updated in real time to show only the lines containing all the said strings (or matching the regexp). This command was mainly designed as a way to search in the shell history, for which it is substantially more efficient than the standard readline ^R binding. With the -v option, it injects the selected line into the tty input buffer, hence allowing the user to edit the line and execute it as a standard command.
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).
vcprompt prints a short string, to be included in your shell prompt, with barebones information about the current working directory for various version control systems. It is designed to be small and lightweight rather than comprehensive. It has varying degrees of recognition for Mercurial, Git, Subversion, CVS, and Fossil working copies.
Minix editline is the line editing library from Minix, originally created by Simmule R. Turner and Rich $alz in 1992. It can be linked into almost any program to provide command-line editing and history. The editline library is call-compatible with the FSF readline library, but is a fraction of the size and offers fewer features. It is distributed under a "C News-like" copyright; see the file LICENSE for details.