X-CD-Roast is a flexible frontend for optical disc authoring. It combines command line tools like "cdrecord", "cdda2wav", "readcd" and "mkisofs" into a nice GTK based graphical user interface.
mpg321 is a completely Free drop-in replacement for mpg123. It has been designed to work as a drop-in replacement for mpg123, for the use of front ends, shell scripts, etc. It does all mp3 decoding using the high-quality integer-only MAD library.