I want my Ubuntu to look like Mac OS X. Just icon and theme if possible! Is it possible? Is there any way to install slingshot launcher?
There is a OS X Lion theme for Precise and other versions available in the Noobslab themes PPA.
The full blog post on Noobslab about changing the cursors, installing Cairo Dock for a "OS X"-ish launcher and other ways to max out the OS X feeling like a Apple splash screen can be found here.
In short (for 12.04): you have to add the repository to you sources and install the packages then. To do that open a terminal and enter these commands:
To change your theme, icons and cursors you must use a tool. You can install one like that (again: from a terminal):
As for Slingshot launcher: there is no stable release yet! You could add the elementary-dev/daily PPA and install a unstable version but that bears a high risk for your system!
Here is another way...
This will install the theme. Here is a description for the theme from the WebUpd8 website: