Gstyle is a new full Gnome theme manager with some really great features which I am sure you will love if you like to customize your Desktop look constantly. Gstyle can automatically download and install wallpapers, Xsplash, GTK themes, icon themes, full themes, mouse pointers and more from gnome-look, deviantart, customize.org and others, or directly from the software source. But not only that, Gstyle can show you how a theme (any kind of theme: icons, Emerald, Metacity, etc.) actually looks, not just a preview. You will see what I mean in the screenshots below (3rd screenshot).
Gstyle can also apply different Compiz cube (well, actually Sphere) styles called Cubemodels. I'm sure you're going to love them. Of course, there is still work to do, but Gstyle is still in its infancy, this being the first version ever released. I think we'll see more of Gstyle soon.
A few Gstyle screenshots:
Gstyle Gnome Full Theme Manager also comes with a script to install some applications such as AWN, Cairo-Dock and others, but something required by Gstyle too: Compiz GIT, including the latest plugins (many many new plugins!) (required for Cubemodels only). There is a downside to this script which worked flawlessly for me: it's in French. Yes, even though Gstyle is in English, the script to install Compiz from GIT and the latest plugins (among others) is in French so you can either install Compiz from GIT yourself, or learn French or... use Google Translate. But everything is pretty easy to understand even if you don't know French (or so it seems to me).
Before you proceed with the installation, here is a video with Gstyle in action: