audio (9)
Audacity
http://audacity.sourceforge.net/download/mac
Cross-platform audio editing tool. Very useful for chopping audio or changing formats etc. Capable of multitracking too. If you edit audio, try this before you buy anything else.
Audion
http://panic.com
The once great shareware audio player is now the great freeware audio player. Simple, no fuss.
Crystal VST/AU
http://www.greenoak.com/crystal/
Wicked little freeware synth program. Very powerful.Rax will let you try this out. (http://www.grantedsw.com/rax)
GimmeSomeTune
http://members.chello.at/eternalstorms/try.html
Cool tool which adds an iTunes menubar item and gives more control to iTunes. Also displays album art as a track plays. UB.
MidiKeys
http://www.manyetas.com/creed/midikeys.html
Lets you use your computer keyboard to send MIDI signals. Awesome to turn your Mac into an instant synthesiser or drum machine instrument! Check out Rax too.
MidiPipe
http://homepage.mac.com/nicowald/SubtleSoft/
Gives you very fine control over MIDI signals. Can be use to transpose, microtune, use chords etc.
OSS3D
http://www.subband.com/
Great plugin for iTunes to give incredible versatility with sound equalization, 3D surround and other cool stuff.
SoundFlower
http://www.cycling74.com/products/soundflower
Free interapplication audio router. Lets you route audio from any application to another.
WireTap
http://www.ambrosiasw.com/utilities/wiretap/
Lets you record audio from any source or application. Very useful for recording internet streams. WireTap Pro is technically shareware, but there is no time limit on the free version.