Mp3Tools, despite the name, should work for all MPEG audio files.
It currently includes three programs, Mp3id3, Mp3info and Mp3index.
Mp3id3 lets you view and edit the ID3 tags of MPEG audio files. Mp3info tells you the MPEG version, its layer and its bitrate. You can also play length of an MPEG audio file.
Mp3index generates customized indexes of your MPEG audio files. It is extremely powerful and includes a nice sample format.
A Perl module, which lets you do anything that Mp3info or Mp3id3 can do, is included.
MP3::Info perl module