Best Free Software for Linux

"... LiVES is a Video Editing System. It is designed to be simple to use, yet powerful. It is small in size, yet it has many advanced features ...":
http://lives.sourceforge.net/

kissdb - (Keep It) Simple Stupid Database

Features:

* Tiny, compiles to ~4k on an x86_64 Linux system
* Small memory footprint (only caches hash tables)
* Very space-efficient (on disk) if small hash tables are used
* Makes a decent effort to be robust on power loss
* Pretty respectably fast, especially given its simplicity
* 64-bit, file size limit is 2^64 bytes
* Ports to anything with a C compiler and stdlib/stdio
* Public domain

https://github.com/zerotier/kissdb

TreeLine stores almost any kind of information in an organized tree structure. Each node in the tree can contain several fields, forming a mini-database:
http://sourceforge.net/projects/treeline/

"... Prey lets you keep track of your laptop, phone and tablet whenever stolen or missing -- easily and all in one place. It's lightweight, open source software that gives you full and remote control, 24/7 ...":
http://preyproject.com/

pdf2htmlEX renders PDF files in HTML, utilizing modern Web technologies. It aims to provide an accuracy rendering, while keeping optimized for Web display:
http://coolwanglu.github.io/pdf2htmlEX/

BZFlag is a free online multiplayer 3D tank battle game:
http://bzflag.org/

Blinken is the KDE version of the well-known game Simon Says. Follow the pattern of sounds and lights as long as you can! Press the start game button to begin. Watch the computer and copy the pattern it makes. Complete the sequence in the right order to win:
http://edu.kde.org/blinken/

StepMania is a free dance and rhythm game:
http://www.stepmania.com/

Kile is a user-friendly TeX/LaTeX editor for the KDE desktop environment:
http://kile.sourceforge.net/

Shotcut is a free, open source, cross-platform video editor:
http://www.shotcut.org/bin/view/Shotcut/WebHome

"... xxxterm is a minimalist web browser with sophisticated security features designed-in, rather than through an add-on after-the-fact. In particular, it provides both persistent and per-session controls for scripts and cookies, making it easy to thwart tracking and scripting attacks.

In additional to providing a familiar mouse-based interface like other web browsers, it offers a set of vi-like keyboard commands for users who prefer to keep their hands on their keyboard.

The default settings provide a secure environment. With simple keyboard commands, the user can "whitelist" specific sites, allowing cookies and scripts from those sites ...":
https://opensource.conformal.com/wiki/XXXTerm

Bitfighter is a fast-paced team-based outer-space multi-player combat game:
http://bitfighter.org/

Cyphertite Basic - online backup:
https://www.cyphertite.com/

Platinum Arts Sandbox Free 3D Game Maker is an open source easy to use standalone 3D Game Maker and 3D Game Design program currently based on the cube 2 engine being used in many schools throughout the world that allows kids and adults to create their own video games, worlds, levels, adventures and quests, even cooperatively:
http://www.sandboxgamemaker.com/

"... RabbitVCS is a set of graphical tools written to provide simple and straightforward access to the version control systems you use. We provide multiple clients and extensions designed to give you a uniform experience no matter what development tools you use ...":
http://www.rabbitvcs.org/

Gobby is a free collaborative editor supporting multiple documents in one session and a multi-user chat:
http://gobby.0x539.de/trac/

Geeknote — non official command line client for Evernote:
http://www.geeknote.me/

Phatch is an user friendly, cross-platform Photo Batch Processor and Exif Renamer with a nice graphical user interface:
http://photobatch.wikidot.com/

Ocenaudio is a cross-platform, easy to use, fast and functional audio editor. It is the ideal software for people who need to edit and analyze audio files without complications:
http://www.ocenaudio.com.br/

Geary is a lightweight email program designed around conversations and built for the GNOME desktop:
http://www.yorba.org/projects/geary/

Glances is a cross-platform curses-based monitoring tool:
http://nicolargo.github.io/glances/

Format Junkie is a Graphical User Interface application with lots of options, which can convert your media files to all the popular formats:
http://www.reddit.com/r/Ubuntu/comments/ya3u4/format_junkie_fully_featur...

ReText is a simple editor that reads your text with MarkDown or HTML markup and saves it as plain text, HTML or PDF:
http://sourceforge.net/projects/retext/

Dead Cyborg (Episode 1 and 2) - free old school sci-fi adventure game:
http://www.deadcyborg.com/
http://www.youtube.com/watch?v=euGnVNNfMhE
http://www.youtube.com/watch?v=O_2wCGEV3aI

"... Monitorix is a free, open source, lightweight system monitoring tool designed to monitor as many services and system resources as possible. It has been created to be used under production Linux/UNIX servers, but due to its simplicity and small size can be used on embedded devices as well ...":
http://www.monitorix.org/

XnSketch allows you to turn your photos into cartoon or sketch images:
http://www.xnview.com/en/xnsketch/

XnRetro allows you to create stunning images with vintage or instant effect on your Desktop:
http://www.xnview.com/en/xnretro/

"... LFTP is a sophisticated ftp/http client, and a file transfer program supporting a number of network protocols. Like BASH, it has job control and uses the readline library for input. It has bookmarks, a built-in mirror command, and can transfer several files in parallel. It was designed with reliability in mind ...":
http://lftp.yar.ru/

yEd is a powerful desktop application that can be used to quickly and effectively generate high-quality diagrams:
http://www.yworks.com/en/products_yed_about.html

zuluCrypt is a front end to cryptsetup, a Linux native solution for hard drive encryption. As a GUI frontend, zuluCrypt makes it easy to use cryptsetup to manage PLAIN,LUKS as well as TRUECRYPT encrypted volumes.

Features:

- Create encrypted volumes in files and in partitions.
- Create LUKS and PLAIN encrypted volumes
- Open encrypted volumes residing in both files and partitions.
- Add keys to luks based encrypted volumes residing in both files and partitions.
- Delete keys from luks based encrypted volumes residing in both files and partitions.
- Open encrypted volumes using a passphrase, a keyfile, a combination of passphrase and keyfile, a gpg encrypted keyfile.
- Retrieve volume keys from either gnome's keyring or kde's kwallet.
- Encrypt stand alone files, a la gpg (no compression and integrity check though).
- Erase data on partitions.

http://code.google.com/p/zulucrypt/

GoAnywhere OpenPGP Studio is a free desktop tool that makes it easy to protect sensitive files using the popular Open PGP encryption standard:
http://www.goanywheremft.com/products/openpgp-studio

Mixxx - free DJ software:
http://www.mixxx.org/features/
http://www.mixxx.org/download/

XnViewMP is the enhanced version to XnView. It is a powerful cross-platform media browser, viewer and converter. Compatible with more than 500 formats (both 32 and 64 bit versions are available):
http://www.xnview.com/en/xnviewmp/

Jitsi (formerly SIP Communicator) is an audio/video and chat communicator that supports protocols such as SIP, XMPP/Jabber, AIM/ICQ, Windows Live, Yahoo! and many other useful features:
https://jitsi.org/Main/HomePage

Radio Tray is an online radio streaming player that runs on a Linux system tray. Its goal is to have the minimum interface possible, making it very straightforward to use:
http://radiotray.sourceforge.net/

Great Little Radio Player - A robust internet radio station streamer for Ubuntu and Fedora based Linux distributions. It connects to web sites offering radio streaming and lets you play radio stations directly from that locations. With Great Little Radio Player, you will have collection of 300 radio stations worldwide:
https://sites.google.com/site/glrpgreatlittleradioplayer/home

Tabula helps you liberate data tables trapped inside PDF files:
http://source.mozillaopennews.org/en-US/articles/introducing-tabula/
https://github.com/jazzido/tabula#readme

Tor Browser Bundle for GNU/Linux - Everything you need to safely browse the Internet. This package requires no installation. Just extract it and run:
https://www.torproject.org/download/download-easy.html.en#linux

Instructions:
https://www.torproject.org/projects/torbrowser.html.en

FSGamer runs games in their own X server, which can improve the speed, reduce annoying interruptions, and make switching between fullscreen games and your desktop easy and reliable (still in alpha):
http://michaelb.org/projects/fsgamer/

The Connection Manager (ConnMan) project provides a daemon for managing internet connections within embedded devices running the Linux operating system.

ConnMan is designed to be slim and to use as few resources as possible, so it can be easily integrated. It is a fully modular system that can be extended, through plug-ins, to support all kinds of wired or wireless technologies. The plug-in approach allows for easy adaption and modification for various use cases:
http://connman.net/

"... Quod Libet is a GTK+-based audio player written in Python, using the Mutagen tagging library. It's designed around the idea that you know how to organize your music better than we do. It lets you make playlists based on regular expressions (don't worry, regular searches work too). It lets you display and edit any tags you want in the file. And it lets you do this for all the file formats it supports ...":
http://code.google.com/p/quodlibet/

Zero Install is a decentralised cross-distribution software installation system. Other features include full support for shared libraries, sharing between users, and integration with native platform package managers:
http://0install.net/

"... AstroMenace is a brilliant 3d scroll-shooter allowing you to feel the adrenalin rush of a fierce space battle against relentless swarms of alien invaders. Immerse into a decisive battle against tons of cunning foes, face the terrifying bosses and protect your homeland throughout 15 diverse levels of the game. The hardcore gameplay of AstroMenace, packed with pure non-stop action, will become a full scale test for your basic instinct of survival ...":
http://www.viewizard.com/

Blobby Volley 2:
http://sourceforge.net/projects/blobby/

With SubiT, you can download subtitles to your favorite movies and serieses by just right clicking them and executing SubiT:
http://subit-app.users.sourceforge.net/