AudioSlicer 
[en] Chop up your MP3 files the easy way. AudioSlicer is a Cocoa GUI application for Mac OS X 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.
Audio Hijack Pro
[en] Audio Hijack Pro gives you the freedom to listen to audio when you want and how you want. Record any audio with Audio Hijack Pro - it's the cornerstone of your digital audio experience. Exclusively for Mac OS X.
AudioLobe
[en] AudioLobe allows you to alter the speed of audio playback without changing the pitch rate. If you are a musician or interested in audio this means you can slow down complex sequences of audio without the vocal or instruments sounding unintelligi...
Rogue Amoeba
[en] Pick Your Audio Hijack Recording Tool
MacMP3Gain
[en] MacMP3Gain is an AppleScript Studio application which brings an Aqua GUI to the command line version of mp3gain, a utility that performs statistical analysis to determine how loud the MP3 file actually sounds to the human ear and performs lossle...
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ArtToDesktop
[en] This Stay-Open applet will continuously update your desktop picture to the album artwork of the currently playing track.
e=1#arttodesktop
Tracks Without Artwork to Playlist
[en] This script will survey the selected tracks or the selected Playlist for tracks without any artwork and quickly copy them to a new discrete Playlist.
e=1#trackswithoutartwork