For various reasons I've needed a lossless MP3 editor: A program that edits encoded MP3 frames directly, allowing cut and paste operations and volume changes with no degradation of quality. For the PC I've found MP3 Direct Cut, an excellent freeware app. For OS X the options aren't as good. MP3 Trimmer is a program specifically tailored for the job, but the "waveform view" of the current version is a tiny non-resizable rectangle, so small it's almost useless. There are other programs like it, but they don't support visual editing at all. By chance I discovered that Audion includes a lossless MP3 editor with a good looking waveform view, but the implementation has serious bugs that corrupt the display data, screw up the play button, and make edits of large files inaccurate. Worse yet, Audion is no longer in development. I've had to resort to using MP3 Direct Cut via Virtual PC as a workaround.
If anyone has information about a lossless MP3 editor for OS X, one with a decent waveform display (that doesn't have to spend THREE MINUTES pre-caching data on a 1.3Ghz machine in order to work), please let me know.
Some good has come of this struggle: I've split Muslimgauze's "Return of Black September" into the five component tracks it was mixed as. This is a terrific album, and even if the music doesn't grab you, the cover art will: