MP3Gain - A free automatic mp3 volume normalizer.
fre:ac - fre:ac is a audio converter and CD extractor designed for Microsoft Windows, Mac OS and Linux, distributed under the GNU General Public License.
QMP3Gain - Graphical user interface front end supporting MP3Gain engine which analyzes and losslessly adjusts...
File Converter - Convert & compress everything in 2 clicks!
wxMP3gain - Needs to be compiled.
Converter365 - Convert all your files the easy way with converter365.com