It is a plugin for XMMS.
It's main task is to display images : it scans the directory containing the file you are playing, and displays them in its window.
It can be a copy of the cover of the album, but why not putting some photos of penguins, so you can have a nice and relaxing slideshow while listening your favourite music...

Some features :

It creates a personalised skin using the xmms-skin, so your display still looks the way you like it.

You have buttons (play, pause, etc...) So if you want to minimize xmms and just keep coverviewer, you have all control on the song! There is also a right-click menu to control things.

You don't have covers, don't want to scan? No problem! Using file information (tags) to get artist and album, CoverViewer can retrieve covers for you from internet... All automatic! (function easilly configurable)

XMMS, obviously
GTK  (1.2+) and GDK-PIXBUF, they should be installed if you have XMMS :)
id3lib

Python is optional, but if you want to use the cover-autoretrieving functions, it will help!

Source is available, feel free to edit it and send me suggestion or bug reports!
A lot of users ideas have been useful in the past, so please go on!
Send me an email there : Caligari