There are several plugins for beets that require additional packages to
be installed.

See http://beets.readthedocs.org/en/latest/plugins/index.html for a
complate list of plugins

Here are a few which can be enabled by installing additional packages.

discogs: The discogs plugin extends the autotagger's search capabilities
to include matches from the Discogs database. To utilize this plugin you
need to install the audio/py-discogs-client package and then add 'discogs'
to your plugins: line in your config.yaml

chroma: This plugin is for acoustic fingerprinting, you will need to
install the audio/py-acoustid package and add 'chroma' to the plugins:
line in your config.yaml

replaygain: This plugin adds support for ReplayGain, a technique for
normalizing audio playback levels. You will need to install the
audio/mp3gain or audio/aacgain packages and add 'replaygain' to the
plugins: line in your config.yaml

web: The web plugin lets your browse and listen to your library through
an HTML5 compatible browser. You will need to install the www/py-flask
package and add 'web' to the plugins: line in your config.yaml
