AudioSlicer is a Cocoa GUI application that finds all silences in an audio file and allows you to split it into several smaller audio files and to name/tag them properly. For now only MP3 is supported but other audio formats may be added in the future.
(shareware) lets you split huge MPEG-2 files in smaller chunks of size specified by user. It is also possible to extract a single segment of the file, given the starting and ending offset
Octave Shifter 2 is a free real-time pitch shifting audio effect for Apple's Audio Unit architecture. By leveraging existing technologies like CoreAudio, Altivec and SSE, Octave Shifter 2 offers a unique audio experience.
xEQ is a parametric EQ/Tone Control Audio Unit. It consists of Low and High shelf filters and three Peak/Cut filters. It is very useful for placing around distortion effects.