If you really want to change the look and feel of your device the best way to do so is to add a custom theme. You could go with a launcher icon theme, but that would more than likely feel incomplete. For a more thorough themeing experience you will want to install a rom like CyanogenMod or any rom based on CM. The CM theme chooser allows you to customize the look of your entire rom including the full framework and system UI.
My favorite new theme is by "CynosureArts" and is called Graphi. The Graphi theme brings a darked out color scheme based on the color of Graphite! The inclusion of stark white on top of the Graphite backgrounds really gives this theme a super clean look. There are over 36 apps that have been fully themed to match the Graphite color scheme of the systemui and framework. There are more than 1800 themed icons included. Head to the link below for the free download.
via XDA