Audacity
Audacity records and edits sounds with aplomb, with tons of new features constantly being added.
Audio
Cog
An open source audio player for OS X (10.4 and above) that supports the following formats: Ogg Vorbis, Mp3, Flac, Musepack, Monkeys Audio, Shorten, Wavpack, AAC, and Wave/AIFF.
LMMS
Create melodies and beats, synthesizing and mixing sounds, arranging samples and much more. The playback with a typing or MIDI keyboard. Bundled with ready-to-use content.
Macsome Audio Editor
Quickly cut, trim or split audio files, using MP3 and AAC formats without quality loss. Other features include fade in and out, volume adjustment and ID tags. Can be used to create ringtones for phones (including iPhone) that use MP3 or AAC.
RGB MusicLab
Ever wonder what a musical Mona Lisa would sould like? RGB MusicLab takes the pixels in a painting, judges their colours and brightness, then interprets them to create music. Don’t like what you hear? There are many options to adjust your final composition.
Riffworks T4
Guitar recording and online collaboration program includes looped recording, automatic track creation, InstantDrummer, effects, song posting, online collaboration, and a tutorial in 14 languages. You can record songs online with friends for free.
Tomahawk
Open source music player without the iTunes bloat allows you to gather all your music sources and downloads in one place. Create playlists, invite friends, listen to radio stations.
VirtualDJ Home
Use beatlock engine to stay on beat and work mixes faster. Loop engine and synchronized sampler let you perform remixes on the fly. Video engine lets you mix and scratch music videos or karaoke as easily as audio.
X Lossless Decoder
Decode, convert and play lossless audio files. Audio files can be split into tracks with a cue sheet when decoding. Supported formats include: (Ogg) FLAC (.flac/.ogg), Monkey’s Audio (.ape), Wavpack (.wv), TTA (.tta), Apple Lossless (.m4a) [10.4 and later], AIFF, WAV.