Here's a quick primer on enabling tracking mechanism in Google Analytics. [source: Google Analytics Help]
Track clicks on links that lead to file downloads (such as PDF, AVI, or WMV)
Track which advertisers are popular by tracking clicks on banners ads where visitors click on to leave your site.
To track outbound clicks on an animated GIF or other type of static banner ad, add the following code within the <a> tag (You may use any folder/filename structure that you desire)
The equivalent code for a Flash banner is provided below:
Track clicks on outbound links that lead visitors away from your site.
Or, to log a rollover event:
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Screenshots of Google Analytics system
The circle of analytics