I installed a few hacks to make my ubuntu look as much like a mac as possible. The end result is really impressive. It’s almost like I have a Macintosh… But its about 90% more useful and customizable. 
First: Get a dock.
I use AWN (Avant Window Navigator)
The installation is simple.
Get the latest version from getdeb.net http://getdeb.net/. I used version 0.2.1 from here: http://getdeb.net/release.php?id=1865
The newer versions support drag ‘n drop for placing your launchers. Here is a screen:
Step 3: The wallpaper
Here you go (click to enlarge):
Step 4: Get a cool mac-like theme.
I used Humanoid - OSX - Dark from gnome-look.org
here is a link: http://gnome-look.org/content/show.php/Humanoid+-+OSX+-+Dark?content=72337
Step 5: Hack your metacity buttons to show on the left. (I’m not sure this will work if you use Emerald)
Open gconf-editor. alt+f2 then run:
gconf-editor
Edit the key: apps> metacity > general
Set to button_layout to:
close,minimize,maximize:menu
Step 6: Install global_menu
Install dependencies:
sudo aptitude install liborbit2-dev libgnomeui-dev libglade2-dev libbonoboui2-dev libglib2.0-dev libpango1.0-dev libatk1.0-dev libcairo2-dev libx11-dev libxext-dev libxinerama-dev libxi-dev libxrandr-dev libxcursor-dev libxfixes-dev libxcomposite-dev libxdamage-dev libcairo-directfb2 libcairo-directfb2-dev libcairo2-dev
Open a terminal
Create a folder
sudo mkdir global-menu-install
* Go to this folder
cd global-menu-install
* Get the patched gtk debs with the following instruction
wget http://gnome2-globalmenu.googlecode.com/files/gtk2.0-ubuntu-gutsy.tar.gz
* Unarchive them
tar zxvf gtk2.0-ubuntu-gutsy.tar.gz
* Install them
1. cd gtk
2. sudo dpkg -i *.deb
* Get the MacMenu applet files
1. cd ..
2. wget http://gnome2-globalmenu.googlecode.com/files/gnome2-globalmenu-applet_0.3.397-1_i386.deb
* Install it
sudo dpkg -i gnome2-globalmenu-applet_0.3.397-1_i386.deb
* Right-click on the panel and click add to the panel. Look for Global Menubar. Add it. And voila. It should work.
The finished product (click to enlarge):
Thanks to:
https://wiki.ubuntu.com/global_menu
http://code.google.com/p/gnome2-globalmenu/wiki/InstallingonUbuntu