Lua is a powerful, light-weight programming language designed for extending applications. The language engine is accessible as a library, having a C API which allows the application to exchange data with Lua programs and also to extend Lua with C functions. Lua is also used as a general-purpose, stand-alone language through the simple command line interpreter provided.

Busybox contains a very small yet fully functional RFC compliant DHCP client udhcpc.

IBus is an Intelligent Input Bus. It is a new input framework for the Linux OS. It provides full featured and user friendly input method user interface. It also may help developers to develop input method easily.

The Courier mail transfer agent (MTA) is an integrated mail/groupware server based on open commodity protocols, such as ESMTP, IMAP, POP3, LDAP, TLS, and HTTP. Courier provides ESMTP, IMAP, POP3, webmail, and mailing list services within a single, consistent, framework.

nov.el provides a major mode for reading EPUB documents (ebooks) in Emacs.