Recently I wrote an mp3 CD to play in my car. Every time a certain song played, the volume would be so high that I would have to frantically search for the volume knob before I loose my eardrums :P
MP3Gain is the opensource solution to this problem. MP3Gain analyzes and adjusts mp3 files so that they have the same volume. Also, the changes MP3Gain makes are completely lossless. There is no quality lost in the change because the program adjusts the mp3 file directly, without decoding and re-encoding.
There are two modes in MP3Gain, Track Mode and Album Mode. Track mode volume-corrects a mix of unrelated songs to a selected level. Album mode volume-corrects a collection of related songs.
Personally i prefer the track mode for correcting the volume with a db setting of 92Db.