I thought this was possible, but it doesn't seem like I can do it.
What I'm looking at doing is passing a variable into a facebook iframe application. It doesn't matter how, but I've been trying a couple different methods. If anyone has any idea.
-----edit---------
Yes (to below), I found the items if anyone else looks for this use…
Create links...
$link_params = array(
'item1' => "blah",
'item2' => "blaaaaargh"
);
$encodedParams = urlencode(json_encode( $link_params ));
//added to link as app_data
Get data…
if (!empty($signed_request) && !empty($signed_request['app_data'])) {
$app_data = json_decode($signed_request['app_data'], true);
} //use in your app from here as $app_data['item1']