EJab is a client for the Jabber (www.jabber.org) open standards instant messaging system which is written in Emacs Lisp and runs inside Emacs.
EPT (Emacs Package Tool) is full userspace package managing tool for GNU/Emacs.
elmake is a way to provide makefiles for elisp packages (for emacs) which are processed completely in Elisp (no external autoconf, make etc. required). For info files, an external makeinfo is suggested, as elisp parsing of info files is slow.