mp3DirectCut is a small and efficient tool for editing MP3 directly.
You can grab it here: http://www.rz.uni-frankfurt.de/~pesch/#mp3dc (http://www.rz.uni-frankfurt.de/~pesch/#mp3dc)
Without the need for decompressing your MP3 into a PCM format you can remove parts, change the volume or copy several regions out of it. This saves work, encoding time and disk space. And there is no quality loss through any re-compressions!
Trim your CD grabbings or your directly to MP3 recorded vinyls or tapes. Cut favourit songs from longer MP3 radio or live recordings. Make multiple cuts and remove everything you want in frame resolution from MP3 files.