iGain is an interactive front-end for the MP3Gain and AACGain programs, designed to integrate with iTunes.
MP3Gain and AACGain use the Replaygain algorithm to compute the overall loudness of a track or album as perceived by the human ear. It then adjusts the track’s volume, so that your tracks or albums appear to play at approximately the same volume. This avoids the need to constantly adjust the volume of your PC or iPod when switching from track to track.
iTunes integration allows iGain to automatically locate your music files, operate on playlists, and tag files so they will be resynced with your iPod after gain adjustments.
iGain is freeware, released under the GNU Public License.
Download: iGain 1.1 Windows 2000/XP