Are you looking for icons, backgrounds, color schemes, window decorations, system sounds, or entire themes? KDE-Look.org ("EyeCandy for your KDE Desktop") provides exactly that. While relatively low on quantity, quality is very high. The layout and interactive nature of this site indicates that it may very well wind up being a central resource for the kind of user who likes to change his colors, icons and look every hour. It also has sections for skins for Noatun and other KDE apps.