I'm very sure you wanted at some point in time to change the look of your Ubuntu installation but had some difficulties doing so. No problem, that's why I made this short tutorial that will explain you how to change your installation icons and bring that unique feeling to Ubuntu.
First of all, go to gnome-look and browse some set of icons. I chosed this one to use it in this tutorial because I really like the icons.
When you got to your icon package website, make sure you download and save the file anywhere, I suggest on your Desktop just because it's faster.
After download you will end up with a .tar.bz2 file which we will use it straight away, as it is, without any extraction of files.
Go to System > Preferences > Appearance and press on the Install button and chose your previously downloaded file.
after you chose it, wait for a couple of seconds for it to load, you will be asked if you want to apply those icons. Press Apply New Theme.
If you later decide to move to a theme and just change the icons it uses, select the theme you want to apply (for example: ClearLooks, Dust) and press Customize and go to Icons tab and chose the icon set you wish to use along with your theme.
This was all, enjoy your new icons!