Kemikal for GTK.
Requires the pixmap and mist engine.
Metacity theme and start-here.png icon included.
Icons are XubuntuStudio from xfce-look.org
Font is AvantGarde LT Medium.
To use the start-here.png icon you'll need to check your icon theme. It should be located in /home/username/.icons/
(Press ctrl+h in your file manager to view hidden folders.) If you don't have the .icons folder you can create one and put your icon sets there. (This may however be different if you use any other dist than Debian/Ubuntu. If so, then open gconf editor and select to use a custom icon for the applications menu.)
Go to /.icons/your icon theme/scalable/places/ and see if you have a start-here.svg icon. If you have one, make a backup of it and remove the original. Now go to (or create) the 48x48/places/ folder and make a backup of the start-here.png icon (if any). Then put the start-here icon from Kemikal in that folder. Open a terminal and write killall gnome-panel
to refresh the panels.Update:
Another color option included.