Setting And Getting Cookies

To set cookies:
Mage::getModel('core/cookie')->set('cookie_name', 'cookie_value', 0); # session cookie
Mage::getModel('core/cookie')->set('cookie_name', 'cookie_value', 60); #lasts 60 seconds

To get cookies:
Mage::getModel('core/cookie')->get('made_productalerts_stock');