The original vi editor

http://ex-vi.sourceforge.net/

The traditional 4.4BSD /bin/csh C-shell

The traditional 4.4BSD rdist

Resolution tool for Intel i915 video cards

Port of various original plan9 tools

http://tools.suckless.org/9base

Find the country that any IP address or hostname originates from

http://dev.maxmind.com/geoip/legacy

Fast image processing tools based on ImageMagick

http://www.graphicsmagick.org/

Fast pixel formats conversion library

Image processing tools

http://www.ImageMagick.org/

Image processing tools

http://www.ImageMagick.org/

Image processing tools (unstable version)

http://www.ImageMagick.org/

Enhanced Printer Spooler

http://lprng.sourceforge.net/

High-performance CORBA ORB with support for the C language

High-performance CORBA ORB with support for the C language

High dynamic-range (HDR) image file format

http://www.openexr.org/

Language for statistical computing and graphics

http://www.R-project.org/

3-D Athena Widget set that looks like Motif

Formats an ASCII file for printing on a postscript printer

http://www.inf.enst.fr/~demaille/a2ps/

An ascii art library

http://aa-project.sourceforge.net/aalib/

Addressbook program with mutt mail client support

http://abook.sourceforge.net/

D-Bus interface for user account query and manipulation

http://cgit.freedesktop.org/accountsservice/

Receive faxes using sound card and radio

Analog Clock for GNUstep

http://gap.nongnu.org/aclock/index.html

Messaging and Integration Patterns provider

http://activemq.apache.org

Program for sending email messages for CVS repository commits

http://search.cpan.org/dist/activitymail/

ADAMEm is a portable Coleco ADAM and ColecoVision emulator

http://www.komkon.org/~dekogel/adamem.html

Versatile addressbook for GNUstep

http://gap.nongnu.org/addresses/index.html

Goodies for addressbook for GNUstep

http://giesler.biz/bjoern/en/sw_addr.html

Adobe CMap collection

http://partners.adobe.com/asn/tech/type/ftechnotes.jsp

Database library for PHP

http://adodb.sourceforge.net

GNOME Symbolic Icons

Affiche allows people to stick notes

http://www.collaboration-world.com/cgi-bin/project/index.cgi?pid=5

Window manager originally based on the Bowman NeXTstep clone

http://www.afterstep.org/

FTP-like shell for accessing Apple II disk images

High Quality Rendering Engine for C++

http://www.antigrain.com/

Approximate grep (fast approximate pattern-matching tool)

Replacement and extension for Tripwire

https://aide.github.io/

802.11 WEP and WPA-PSK keys cracking program

http://www.aircrack-ng.org/

Morse code training program

http://www.nongnu.org/aldo/

Interpreter for purely symbolic LISP

http://www.t3x.org/alisp/

Cross-platform library for games and multimedia programming

https://liballeg.org/

Asteroids clone by Allen Smith

http://www.integrity.com/homes/tomandkaren/Allenroids/

Mail and news client descended from Pine

https://www.washington.edu/alpine/

ALSA compatibility library

http://www.alsa-project.org/

ALSA compatibility library plugins

http://www.alsa-project.org/

Extremely fast program for analysing WWW logfiles

http://www.analog.cx/

ANother Tool for Language Recognition

https://www.antlr2.org/

Ncurses based arcade game with only 64 lines of code

http://aop.raffi.at/

Java- and XML-based build tool, conceptually similar to make

http://ant.apache.org/

Version 2.2.x of Apache web server with prefork MPM.

http://httpd.apache.org/