Mailcrypt
  
   Mailcrypt is an Emacs interface to PGP, written by Patrick LoPresti
   <patl@lcs.mit.edu> and Jin Choi <jin@atype.com>. It works, it installs
   without hassle, and integrates very easily. Mailcrypt can be obtained
   from
   <URL:http://www.nb.net/~lbudney/linux/software/mailcrypt.html>.
   
  Tools for Mime
  
   Tools for Mime is an Emacs MUA interface to MIME written by MORIOKA
   Tomohiko <morioka@jaist.ac.jp>, and KOBAYASHI Shuhei
   <shuhei-k@jaist.ac.jp>.
   
   Note:Do not use TM with Gnus 5.8.x or later. These versions of Gnus
   have native MIME support and should not try to use an external MIME
   library.
   
   It can be obtained from
   <URL:ftp://ftp.jaist.ac.jp/pub/GNU/elisp/mime/>. It has mirrors at:
   <URL:ftp://ftp.nis.co.jp/pub/gnu/emacs-lisp/tm/> (Japan)
   <URL:ftp://ftp.nisiq.net/pub/gnu/emacs-lisp/tm/> (USA)
   <URL:ftp://gnus.xemacs.org/pub/mime/jaist.ac.jp/> (USA)
   <URL:ftp://ftp.unicamp.br/pub/mail/mime/tm/> (Brasil)
   <URL:ftp://ftp.th-darmstadt.de/pub/editors/GNU-Emacs/lisp/mime/>
   (Germany)
   <URL:ftp://ftp.tnt.uni-hannover.de/pub/editors/xemacs/contrib/>
   (Germany).
   
   To use with Gnus add the line
(load "mime-setup")

   to your .emacs file before you initialize Gnus.
   
   Alternately, you can use gnus-setup.el to activate tm, bbdb,
   supercite, and other packages. See Question #2.12 for details.
   
   If you are using an XEmacs version of 19.15 or newer, you do not need
   tm as it is now included standard with XEmacs.
   
  Group Lens
  
   Group Lens is a collaborative filtering system that helps you work
   together with other people to find the quality news articles out of
   the huge volume of news articles generated every day. It was written
   by Brad Miller <bmiller@cs.umn.edu> as his PhD thesis. It is now
   distributed as a standard part of Gnus. A copy for Gnus 5 can be
   obtained at:
   <URL:http://www.cs.umn.edu/Research/GroupLens/>.
   
  Insidious Big Brother Database
  
   BBDB is a rolodex-like database program for GNU Emacs created by Jamie
   Zawinski <jwz@netscape.com> of Netscape fame. Jamie has recently given
   his blessing to a new version whose primary maintainer is Ronan Waide
   <waider@waider.ie>. This version is the result of the fork that was
   maintained by Matt Simmons for some time. The new home of BBDB is
   <URL:http://bbdb.sourceforge.net/> and considered official and
   somewhat stable.