This isn't a direct answer as this has already been answered, but everyone was talking about sending the data, but nobody really said what you do when it gets there, and it took me a good half an hour to work it out. So I thought I would help out here.
I will repeat this bit
$data = array(
'cat' => 'moggy',
'dog' => 'mutt'
);
$query = http_build_query(array('mydata' => $data));
$query=urlencode($query);
Obviously you would format it better than this www.someurl.com?x=$query
And to get the data back
parse_str($_GET['x']);
echo $mydata['dog'];
echo $mydata['cat'];