function subscribe() {
    var email = $('email').value;
    
    new Json.Remote('/rpc/subscribe/', {
        onComplete: function(response) {
            alert(response.message);
        }
    }).send({'email_address': email});
}

window.addEvent('domready', function() {
    $('subscribe-button').addEvent('click', function() {
        subscribe();
    });
});