Win32 dll to normalize wav pcm files using very well known replaygain algorithm, it can be used as the first pass prior to mp3 encode, notice that BENormalize that is available in the project http://sourceforge.net/projects/rsppmp3/ gives a lot better results than ReplayGain, give it a try
NorQualizer is a smart audio equalizer/normalizer which corrects audio files to get them all similar in terms of bandwidth and volume level. Especially useful for preparing audio CDs with files from different sources.
GNoise is a GTK+ based wave file editor. It uses a display cache and a
double-buffered display for maximum speed with large files. It supports
common editing functions such as cut, copy, paste, fade in/out, normalize
and more with unlimited undo.