MP3 Editor
I found a program called AudaCity that has done pretty well so far editing my MP3 files. When you obtain these things, sometimes they have problems. This thing fixes them pretty well.
You need the Lame_enc.dll to save MP3 format. This is the problem with open source. They can't include it because of distribution rights. They make it easy enough to install though.
Some dope out there thinks it is better to record one long MP3 instead of breaking things up into manageable pieces. This software makes it easy to highlight chunks and save as MP3. This would work well for converting old tapes or even (heaven forbid) records, if you are in to that sort of thing.