Emacs has various extremely nice packages available for it, all written in the powerful and interesting programming language, elisp. Here are some of my favorites:
- Gnus - complete E-mail and Usenet News reader. Well, that's an understatement. It's more like a way of life. Or deeper meaning of "existence". Or something. I never figured out why they called nedit a "nirvana editor". This editor is more like it. Maybe.
- Mailcrypt - very easy interface for PGP and GnuPG.
- psgml - nice HTML and SGML editing.
- dictionary - interfaces with dict service, integrating a dictionary to the editor. (Somewhat bad interface, though, and doesn't fully do MULE - my ...)
- w3 aka "Gnuscape Navigator". A web browser in Emacs. Not really great one, even in XEmacs where it has graphics support, but will do if you have nothing else... Using E2 is a sheer impossibility with it. (I think it could be used for building an integrated noding environment....)
Of course, there are some packages for Emacsen that are just plain crazy, amazing, impressive, or at least fun:
- doctor (Well, they say LISP is good for AI. This one isn't "intelligent", but is close enough. =)
- dissociated press, spook and yow (good commands for creating "interesting" text...)
- TiMidity (MIDI player/soft synth, that doesn't have an interactive note display mode - except if you use the emacs frontend!)
- Emacs Elite (Well, no 3D engine, but at least the trading works...)