Magento Custom Dropdown Column in Manage Product Grid

Step 1: Create A New Function in From.php

 public function getMainoption()
    {
        $collection = Mage::getModel('mainoption/mainoption')->getCollection();
        $i=0;
        foreach($collection as $main_option)
        {
            $i++;
            $main_option_list[$i]['value'] = $main_option->getMainoptionId();
            $main_option_list[$i]['label'] = $main_option->getTitle();
        }
        return $main_option_list;

    }


Setp 2 :  Use this Function


 protected function _prepareForm()
  {
      $form = new Varien_Data_Form();
      $this->setForm($form);
      $fieldset = $form->addFieldset('suboption_form', array('legend'=>Mage::helper('suboption')->__('Item information')));

   

 $mainoptionlist = $this->getMainoption();
 $fieldset->addField('mainoption', 'select', array(
          'label'     => Mage::helper('suboption')->__('Main Option List'),
          'name'      => 'mainoption',
          'values'    => $mainoptionlist
 ));


}