System Host File

Redirects in your hosts file

This method is pretty straight forward, available on all systems and works with all browsers. The host file information on where to find a host in a network and maps host names to IP addresses.
You find this file in the following locations depending on your operating system:

Windows NT/2000/XP/Vista:

%SystemRoot%\system32\drivers\etc\hosts %SystemRoot% in most cases is C:\WINDOWS

Linux/Unix:

/etc/hosts

Mac OS X:

/private/etc/hosts

You can edit this file with your favorite text editor and add the following lines to not display GoogleAds:

# [GoogleAds]
127.0.0.1  pagead.googlesyndication.com
127.0.0.1  pagead2.googlesyndication.com #[Google AdWords]
127.0.0.1  adservices.google.com
127.0.0.1  imageads.googleadservices.com #[Ewido.TrackingCookie.Googleadservices]
127.0.0.1  imageads1.googleadservices.com
127.0.0.1  imageads2.googleadservices.com
127.0.0.1  imageads3.googleadservices.com
127.0.0.1  imageads4.googleadservices.com
127.0.0.1  imageads5.googleadservices.com
127.0.0.1  imageads6.googleadservices.com
127.0.0.1  imageads7.googleadservices.com
127.0.0.1  imageads8.googleadservices.com
127.0.0.1  imageads9.googleadservices.com
127.0.0.1  partner.googleadservices.com
127.0.0.1  www.googleadservices.com
# [Google Analytics]
127.0.0.1  apps5.oingo.com #[Microsoft.Typo-Patrol]
127.0.0.1  www.appliedsemantics.com
127.0.0.1  service.urchin.com #[Urchin Tracking Module]
127.0.0.1  ssl.google-analytics.com #[urchinTracker]
127.0.0.1  www.google-analytics.com #[Google Analytics]

This will redirect requests to your local machine. Check this http://everythingisnt.com/hosts if you want to block more advertising providers and spam sites.