iCan is an intelligent, community-driven command line that helps you to automate any kind of task arising in your daily Linux use. It is extensible through simple Lua modules, which run in a sandbox environment. It is designed to learn what you do and make things easier for you, every time you do something.
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.
rgxg (ReGular eXpression Generator) is a C library and a command-line tool that generate (extended) regular expressions. It can be useful for generating expressions that match, for example, a specific number range (e.g. 0 to 31 or 00 to FF) or all addresses in a CIDR block (e.g. 192.168.0.0/24 or 2001:db8:aaaa::/64).
utfout is a command-line tool that can produce UTF-8 (Unicode) strings in various ways and direct them to standard output, standard error, or direct to the terminal without the need for shell support. Strings can be repeated, delayed, randomly-generated, written to arbitrary file descriptors, interspersed with other characters, and generated using ranges. printf(1)-style escape sequences are supported along with extended escape sequences. utfout(1) sits somewhere between echo(1) and printf(1).
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).