[Editor's note: In case you'd like to install this yourself from source, it's not that difficult. You'll need the Dev Tools installed, of course, but after that, just download the 0.59r source from the mpg123 homepage linked above, then visit the mpg123 OS X port page on SourceForge and download the patch files. Expand the archive, then read and follow the directions in README.MACOSX (basically rename a file, then 'make macosx' and 'sudo make install'). Once installed, typing 'mpg123 /path/to/mp3_file' will play the specified MP3 file. Type 'mpg123' without any parameters to see a command list.]

