deadsea - 5:03 pm on Oct 5, 2012 (gmt 0)
I do it like this:
<a href="http://othersite.example.com/" onclick="this.href='http://mysite.example.com/track?url='+escape(this.href)">Click Here</a>
Dynamically add your tracking url onclick. Your tracking url then has to redirect the user to the right place.
Googlebot still sees the original url, as do users when they mouse over.