cdcover analyses MP3s and other audio files, generating a picture of the waveform for each track, suitable as "album art" for an ID3 tag, or for combining as a single "CD cover"
To convert a bunch of mp3s into ./png/esquivel/*.png output files...
./process.sh -e -s -f -w 5 -m -o png/esquivel esquivel/*.mp3
sox, mp3info, ruby, rmagick
Tested with sox v14.0.0, MP3Info 0.8.4, ruby 1.8.6 (2007-09-24 patchlevel 111), RMagick 2.9.1.
It does somewhat assume you've installed RMagick using rubygems and will probably break if you don't have rubygems anywhere. Easily rectified by deleting the first line of cdcover.rb.
You can also clone the project with Git by running:
$ git clone git://github.com/rjp/cdcover