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).