HN does something similar. When you up/down vote something, it creates a new js Image object and sets the src to the HN site, which then pings the server. No need for ajax.<p><code>
var score = byId('score_' + item);
var newscore = parseInt(score.innerHTML) + (v[0] == 'up' ? 1 : -1);
score.innerHTML = newscore + (newscore == 1 ? ' point' : ' points');<p><pre><code> // hide arrows
byId('up_' + item).style.visibility = 'hidden';
byId('down_' + item).style.visibility = 'hidden';
// ping server
var ping = new Image();
ping.src = node.href;</code></pre>
</code>
Here's another blog post with even more information on what parameters are being sent to Google during the click: <a href="http://www.razzed.com/2009/02/12/analysis-of-google-outbound-link-tracking/" rel="nofollow">http://www.razzed.com/2009/02/12/analysis-of-google-outbound...</a>
If you are logged into Google, it sends more info using a different function<p>For Example:
return rwt(this,'','','res','1','AFQjCNEdw7LJgOmjlxPAZ-jF7e3aPy1bbQ','&sig2=D3Wg-V0MDjmRS-gqjk66rA','0CAkQFjAA')
Did this just change or something? Earlier today I did a search and copied the URL and it was something like <a href="http://www.google.com/url?url=http%3A%2F%2F.." rel="nofollow">http://www.google.com/url?url=http%3A%2F%2F..</a>. But just now when I tried to duplicate it, I didn't get that. Weird.