Audacity is a cross-platform multitrack audio editor. It allows you to record sounds directly or to import Ogg, WAV, AIFF, AU, IRCAM, or MP3 files. It features a few simple effects, all of the editing features you should need, and unlimited undo. The audio I/O uses PortAudio, which fully supports OSS, Mac OS X CoreAudio, and Windows WMME, and can be compiled with support for ALSA and Jack.
The MusicBrainz client library (also known as mb_client or libmusicbrainz) is a library for developers that wish to add MusicBrainz metadata lookup capabilities to their applications. It calculates CD Index IDs and Relatable's acoustic fingerprints, and looks up the metadata associated with the calculated IDs.
mp3plot creates a plot (textual or graphical) of the bitrate distribution of an MP3 file. It displays which proportion of the audio file uses each of the possible bitrates. The plot can serve, for example, to compare an audio source as encoded by different encoders or settings or to display how the chosen (average) bitrate was achieved by the encoder.