GnomeShell Reflection is an extension that gives you a classic style desktop. It is mainly designed for the new Guadalinex distro (codename GECOS), but feel free to use it anyway.
See http://www.guadalinex.org/
Because the message tray is moved to the top of the screen I changed some CSS attributes, the message tray gradient and the rounded borders of the notifications. If you want this changes copy gnome-shell.css to /usr/share/gnome-shell/theme folder.
This project is licensed under the terms of the GPL v2.0, see http://www.gnu.org/licenses/gpl-2.0.html