Sweep is an editor for sound samples. It operates on files of various formats
such as .wav, .aiff and .au, and has multiple undo/redo levels and filters.

Sweep features: 
 o Loading and saving of PCM encoded sound formats including AIFF, Sun/NeXT AU
   and WAV. 
 o Multiple views of each sound: you can view different parts of the same sound
   in different windows simultaneously, with variable zooming in each view. You
   can view the entire sound at once, or zoom right down to the individual
   sample values. 
 o Discontinuous selections: you can select regions of a sound with the mouse.
   By holding down the <Shift> key whilst selecting more regions, each region
   is added to the total selection. Also, selection boundaries can be moved,
   and selection regions merged, at any time.
 o Cut, copy and paste: conventional cut or copy selected regions of a sound,
   and paste into the same or other sounds.
 o Multiple undo and redo: all operations are reversible and can be re-applied.
 o Simple effects filters: normalisation (maximal amplification without
   degradation) and time reversing of selected regions. 
 o Playback: playback of entire sound, or of selected regions only. Looped
   playback of entire sound or selected regions. Editing and effects are not
   disabled during playback, giving you instantaneous feedback of the result of
   each action. 
 o Piano-style playback: the computer keyboard keys behave like musical keys
   for playback of instrument samples, so you can hear how the sample will
   sound when used in a sequencer or tracker. 
 o Separate volume levels per view, which can be adjusted with the mouse wheel
   if available. 

WWW: http://sweep.sourceforge.net/