$customerId = Mage::getSingleton('customer/session')->getId();
$quote = Mage::getModel('sales/quote_address')->loadByCustomer($customerId);
...

public function showAllSku(Mage_Sales_Model_Quote_Address $address)
{
    $total = 0;

    foreach ($address->getAllItems() as $item) {

        $product = $item->getProduct();
        $options = $product->getTypeInstance(true)->getOrderOptions($product);

        Mage::Log("SKU: ". $item->getSku(), 7, "model.log");

   }
   return 'true';
}

public function testAction()
{
    $address = ???;   //<-- I need help here
    echo Mage::helper('my_module')->showAllSku($address);
}