GoldWave Audio Editor

I normally use Adobe Soundbooth or Audacity for quick audio edits - however, Goldwave has a feature that is worth the costs of registration - batch processing.  I needed to quickly convert a number of audio files from SWA format (don't ask!) to WAV.  With Goldwave, this is a simple task.  Use Batch Processing to process and convert your complete library of songs: match volume levels of different songs, boost the bass, trim leading and trailing silences, convert to MP3, and much more. Supports iTunes Plus, m4a, wav, wma, mp3, ogg, aiff, au, vox, FLAC, and even raw binary data. Entire folders and subfolders can be processed with just a few clicks and the entire hierarchy preserved.

Check it out:  http://www.goldwave.com/