General:

• Info - Documentation browsing system.
• Texinfo - With one source file, make either a printed manual (through TeX) or an Info file (through texinfo). Full documentation in this menu item.

Emacs:

• Emacs - The extensible self-documenting text editor.
• Elisp - Emacs Lisp Reference Manual.
• GNUS - The news reader GNUS.
• VM - A UNIX mail reader for use in Emacs
• SC - Supercite lets you cite parts of messages you're replying to, in hairy ways.
• VIP - A VI-emulation for Emacs.
• Dired-X - Dired Extra Features.
• Forms - Emacs package for editing data bases by filling in forms.
• Calc - "Calc 2.02" is an advanced desk calculator and mathematical tool for GNU Emacs.
• CL - Partial Common Lisp support for Emacs Lisp.
• ISpell - An interactive spell checker.

GCC:

• GCC - The GNU C/C++/Objective-C compiler.
• CPP - The GNU C preprocessor.
• LibG++ - A set of standard libraries for the GNU C++ environment.
• Iostream - The C++ input/output facility.
• Libobjects - The GNU Objective-C Class Library.
• Gperf - Perfect Hash Function Generator.
• BISON - GNU Project parser generator (yacc replacement)
• GDB - The source-level C debugger.
• Configure - Cygnus configure script.
• Configure Paper - On Configuring Development Tools.

Misc:

• Standards - GNU coding standards.
• GNU make - The GNU make utility for building programs.
• CVS - The CVS code management system.
• Regex - The GNU regular expression library.
• DIFF - GNU diff, diff3, sdiff, cmp
• GZIP - The GNU Zip compression/decompression utility.
• M4 - The GNU version of the macro preprocessor m4.