I used first the theme \"ambiance\" of lucid, and then I changed some colors with gnome-color-chooser.
So first install gnome color chooser, then download sorrow.gnomecc.tar and extract it on your desktop for example. Open gnome color chooser, file -> open -> sorrow.gnomecc. You should now have my configuration.
I use emerald with my personalized theme sorrow : http://gnome-look.org/content/show.php?content=123884
Concerning my wallpaper : http://odwetpozorow.files.wordpress.com/2008/10/night_by_deluze.jpg
For the menu transparency you need to install compiz settings manager, go to accessibility -> opacity, and add this line :
type = dock | dropdownmenu | popupmenu | tooltip
My value is 75.