To make my admin Sales/Orders grid better I added column to the grid:

and as on the picture above it shows order delivery method but ... how to create "delivery method" dropdown list to make it easier to use? So far I tried to add a class:

public function getCarrierList()
{
    $shippingMethods = Mage::getSingleton('shipping/config')->getActiveCarriers();  
    $methods = array();
    foreach($shippingMethods as $method)
    {
            $methods[$method['value']] = $methods[$method['label']];
    }
    return $methods;
}

and added to the column definition:

    $this->addColumn('shipping_method', array(
        'header' => Mage::helper('sales')->__('Shipping Method'),
        'index' => 'shipping_description',
        'type'=> 'options',
        'filter_index' => 'shipping_method',
        'options' => $this->getCarrierList(),
    ));
    

but then my column stays empty and drop-down is also empty. Of course I can live without it but if I can have a list instead of a typing method name .. would be nice.