XSLT-process is a minor mode for (X)Emacs that allows you to run a Java XSLT processor on a buffer and display the result in another buffer, or in a browser. You can also run the XSLT processor in debugging mode, setup breakpoints, run step by step, view local and global XSLT variables, and many more.
refdb-mode is a minor mode for Emacs that implements an interface to RefDB, a reference management and bibliography tool for SGML, XML, LaTeX, and Muse documents. It integrates nicely with psgml, nxml-mode, AucTeX, and muse-mode. refdb-mode provides the complete functionality of the RefDB command line clients from a graphical interface. You can add and edit references, notes, and styles, run queries, and insert the results as citations into your DocBook, TEI, LaTeX, or Muse documents. You can also look up cited references in the database right from your document. You can create, transform, and view these documents with a mouse click. This amounts to an integrated authoring environment for markup languages with reference management and bibliography support.
Jove is a compact, powerful, Emacs-style text-editor. It provides the common emacs keyboard bindings, together with a reasonable assortment of the most popular advanced features (e.g., interactive shell windows, compile-it, language specific modes) while weighing in with CPU, memory, and disk requirements comparable to vi.
Java Development Environment for Emacs (JDEE) is an Emacs-based integrated development environment (IDE) for developing Java applications and applets. Features include multiple code browsers, a JPDA-based debugger, method and field completion, template-based and procedure-based code generation, Java source code interpreter, context-sensitive help, and more.
Aquamacs is a Mac-like version of the powerful Emacs text editor that runs as a standard OS X application. It features extensive customization that enables it to conform better with Apple's standard Human Interface Guidelines (HIG) than standard versions of the editor do. It provides a more Mac-like user experience than Carbon Emacs.
nethack-el is an Emacs major mode for playing nethack. Separate buffers are used for the map, status, messages, and menus. It features customization of keys and colors and user programmable hooks on game events. It supports GNU Emacs 20/21 and XEmacs 21, with graphical tiles on *Emacs 21.