A tip if you are trying to use the ARKAOS Visualizer Plug-In for iTunes on Mac OS X. You can add new .kos files (additional visualizations) from the ARKAOS USER ZONE. Unfortunately when you download these files they are not recognized by the application because there is an "icon recognition" problem. In order to overcome this problem you need to set the file creator and type correctly. You can use a slick little application like DropRetype to make the modification. All of this is explained at the ARKAOS site, but they did not bother to indicate the proper file creator and type. In case you need to know:

Type: KAO1
Creator: KAOS