Banshee, in my opinion, is one of the best things that has happened to the Gnome Desktop. Ever since it became the standard music player packaged with Ubuntu 10.10, it has changed the out-of-the-box Ubuntu experience (I do love me some rythymbox, of course).
One thing that Banshee lacks is some kind of visualization engine. This is something I overlooked at first, but as I began recruiting friends to become Ubuntu users, this question kept popping up.
Well, after some research, I managed to find a pretty decent solution. OpenVP is an open source visualization platform, and since 2008 they have been releasing integrations with Banshee media player.
The banshee integration project is actively developed on gitorious, though you can find a more stable version in the ubuntu/debian package repository
Here is a sample of it at work (this setting is called 'inferno'):

Installing the bugger
Now I bet you want to install it, eh!? Well, here goes.
1. If you are using Debian, you will need to make sure you have made the sid (unstable) package sources available. If you are using Ubuntu, no need to worry, because as of this post, the 1.7.6 version was availble in the universe sources.
2. Now you can install the package from the repositories!
richard@localhost:$ sudo apt-get install banshee-extension-openvp
3. Voila! Restart Banshee (if it was already open), queue up some music, and now you have visualizations in the 'Now Playing' view. Use the controls in the top right.
Next Step: Installing from the Git Repo
The next installment of the banshee-visualizations deal is going to be to install from the gitorius repo, and thus be able to pull live developments! Stay tuned!