There's a couple of apps on the
DJ Tools page that might do the job. Other than that I'd use a program like
CoolEdit . You can load up an MP3 and cut the sections you don't want then resave the existing data into another MP3 file using the 'save as' function and renaming it to a different file name than the original. It can be a bit time consuming but in the end you've got exactly what you want and you don't have to convert to WAV first.