Letter: M
- Macaulay2 - System for algebraic geometry and commutative algebra
- Maelstrom - Space combat game
- MagicPoint - X based presentation software
- MegaMek - A portable, network-enabled BattleTech engine
- MochiKit - A lightweight JavaScript library
- mISDN - Userspace part of Modular ISDN stack
- macchanger - An utility for viewing/manipulating the MAC address of network interfaces
- mach - make a chroot
- machineball - A futuristic ball game with simple rules
- magic - A very capable VLSI layout tool
- magicor - Push ice blocks around to extenguish all fires
- mail-notification - Status icon that informs you if you have new mail
- mailgraph - A RRDtool frontend for Mail statistics
- makebootfat - Utility for creation bootable FAT disk
- man-pages-uk - Ukrainian man pages from the Linux Documentation Project
- manaworld - 2D MMORPG world
- manaworld-music - Music files for the Manaworld game
- manedit - UNIX Manual Page Editor
- mantis - Web-based bugtracking system
- marble - A KDE Desktop Globe
- mathml-fonts - Mathematical symbol fonts
- maxima - Symbolic Computation Program
- mboxgrep - Displays e-mail messages matching a pattern
- mbuffer - Measuring Buffer is an enhanced version of buffer
- mcabber - Console Jabber instant messaging client
- mcpp - Alternative C/C++ preprocessor
- mcrypt - Replacement for crypt()
- mcs - A configuration file abstraction library
- mdbtools - Access data stored in Microsoft Access databases
- mdsplib - METAR Decoder Software Package Library
- meanwhile - Lotus Sametime Community Client library
- mecab - Yet Another Part-of-Speech and Morphological Analyzer
- mecab-ipadic - IPA dictionary for MeCab
- mecab-java - Java binding for MeCab
- mecab-jumandic - JUMAN dictorionary for MeCab
- mediawiki - A wiki engine
- meld - Visual diff and merge tool
- memcached - High Performance, Distributed Memory Object Cache
- memchan - In-memory channels for Tcl
- mencal - Menstruation calendar
- mercator - Terrain library for WorldForge client/server
- mercurial - A fast, lightweight distributed source control management system
- mesa-libGLw - Xt / Motif OpenGL widgets
- metakit - Embeddable database
- metamonitor - A Simple program that watches log files and popup its changes
- metapixel - A Photomosaic Generator
- methane - Super Methane Brothers
- mew - Mew - Messaging in the Emacs World.
- mfstools - Utilities for TiVo drive upgrades
- mftrace - Utility for converting TeX bitmap fonts to Type 1 or TrueType fonts
- mgopen-fonts - Truetype greek fonts
- mhash - Thread-safe hash algorithms library
- mhgui - A simple GUI library for MakeHuman
- mhonarc - Perl mail-to-HTML converter
- miau - Full-featured IRC bouncer
- migemo - Japanese incremental search tool
- milter-greylist - Milter for greylisting, the next step in the spam control war
- milter-regex - Sendmail milter plugin for regular expression filtering
- mimedefang - E-Mail filtering framework using Sendmail's Milter interface
- mimetex - Easily embed LaTeX math in web pages
- mimetic - A full featured MIME library written in C++
- min12xxw - Converts PBM stream to Minolta printer language
- mirage - A fast and simple image viewer
- mirrormagic - Puzzle game where you steer a beam of light using mirrors
- mksh - MirBSD enhanced version of the Korn Shell
- mkvtoolnix - Matroska container manipulation utilities
- mlmmj - Mailserver-independent ezmlm-like mailing list manager
- mlton - Optimizing compiler for Standard ML
- mm - Shared memory allocation library
- mmv - Move/copy/append/link multiple files
- mock - Builds packages inside chroots
- mod_annodex - Apache module for server-side support of annodex media
- mod_auth_pam - PAM authentication module for Apache
- mod_auth_shadow - An Apache module for authentication using /etc/shadow
- mod_cband - Bandwidth limiting for virtual hosts
- mod_dnssd - An Apache HTTPD module which adds Zeroconf support
- mod_extract_forwarded - Extract real source IP for forwarded HTTP requests
- mod_fcgid - Apache2 module for high-performance server-side scripting
- mod_geoip - GeoIP module for the Apache HTTP Server
- mod_mono - A module to deploy an ASP.NET application on Apache with Mono
- mod_nss - SSL/TLS module for the Apache HTTP server
- mod_revocator - CRL retrieval module for the Apache HTTP server
- mod_security - Security module for the Apache HTTP Server
- mod_suphp - An apache2 module for executing PHP scripts with the permissions of their owners
- moin - MoinMoin is a Python clone of WikiWiki
- moin-latex - LaTeX plugin for the MoinMoin wiki
- monkey-bubble - Game in the spirit of Frozen Bubble
- mono-debugger - A debugger for Mono
- monodevelop - A full-featured IDE for Mono and Gtk sharp
- monodoc - The mono documentation system
- monotone - A free, distributed version control system
- monsterz - Puzzle game, similar to Bejeweled or Zookeeper
- moodle - A Course Management System
- moodss - Powerful modular monitoring graphical application
- moomps - Powerful modular monitoring service
- mosml - Moscow ML
- most - more, less, most
- moto4lin - Filemanager and seem editor for Motorola P2k phones
- mousepad - Mousepad - A simple text editor for Xfce
- mozldap - Mozilla LDAP C SDK
- mpc - Command-line client for MPD
- mrxvt - A lightweight multi-tabbed terminal emulator for X
- msmtp - SMTP client
- mtd-utils - Utilities for dealing with MTD (flash) devices
- muParser - A fast math parser library
- mugshot - Companion software for mugshot.org
- muine - Music Player for GNOME
- multican - Remote control utility for Canon cameras
- multiget - An easy-to-use GUI file downloader
- multisync - Calendar (and other PIM data) synchronization program
- multitail - View one or multiple files like tail but with multiple windows
- munin - Network-wide graphing framework (grapher/gatherer)
- museek+ - A Soulseek filesharing client
- musicbox - A simple one-file-at-a-time audio tag editor
- mussh - Multihost SSH wrapper
- mxml - Miniature XML development library
- mysql++ - C++ wrapper for the MySQL C API
- mysql-connector-java - Official JDBC driver for MySQL
- mysql-gui-tools - GUI tools to manage mysql Databases
- mysql-proxy - A proxy for the MySQL Client/Server protocol