Showing software for all platforms
Sauerbraten (a.k.a. Cube 2) is a free multiplayer/singleplayer first person shooter, built as a major redesign of the Cube FPS. Much like the original Cube, the aim of this game is not necessarily to produce the most features & eyecandy possible, but rather to allow map/geometry editing to be done dynamically in-game, to create fun gameplay and an elegant engine. The engine supporting the game is entirely original in code & design, and its code is Open Source (ZLIB license, read the docs for more on how you can use the engine).
Audacity is a free audio editor and recorder for Windows, Mac OS X, GNU/Linux, and other operating systems. You can use Audacity to record live audio, convert tapes and records into digital recordings or CDs, and edit sound files.
Ardour is a digital audio workstation. You can use it to record, edit, and mix multi-track audio. You can produce your own CDs, mix video soundtracks, or just experiment with new ideas about music and sound. Ardour capabilities include multichannel recording; non-destructive editing with unlimited undo and redo; full automation support; a powerful mixer; unlimited tracks, busses, and plugins; timecode synchronization; and hardware control from surfaces like the Mackie Control Universal.
TuxGuitar is a multi-track tablature editor, score writer, and MIDI sequencer written in Java, designed to help guitarists write, edit, and play songs. It has its own file format, and can also import and export Guitar Pro files, import Power Tab and TablEdit tabulatures, and export tabulatures as LilyPond scores, ASCII, MusicXML, and Adobe PDF. It can also load and export MIDI files.
EasyTAG lets you view and edit tags for MP3, MP2, MP4/AAC, FLAC, Ogg Vorbis, MusePack, Monkey Audio, and WavPack files. It can parse file names and directories to automatically fill in fields (using masks), or search Internet tag databases.