I recently had to implement a new grid in Magento, and I wasn’t sure what should I write to the type parameter:

protected function _prepareColumns()
{
      $this->addColumn('some_column_id', array(
              'header' => Mage::helper('core')->__('Some column name'),
              'index' => 'some_column_index',
              'type' => '???',
      ));
...

So I made a little bit of research to find out all the types available. I don’t want to go in details, so here is the list:

• action
• checkbox
• concat
• country
• currency
• date
• datetime
• input
• interface
• ip
• longtext
• massaction
• number
• options
• price
• radio
• select
• store
• text
• theme
• wrapline

You will find all these types in /app/code/core/Mage/Adminhtml/Block/Widget/Grid/Column/Renderer folder. You can also make your own grid types similarly.