Sure, if you go to a toy shop you can pick up funny coloured glasses. Or else wrap your screen in coloured cellophane.

Sorry the answer is no. Your only choice is to try different skins. Go to LW's menu bar, View > Change skins. You can downld extra ones from here http://www.limewire.com/english/content/skins.shtml

Or you can search the forum for people who have offered their own custom skins.