I have the car insurance rider on my AMEX - I got it when I ditched my Diner's Club.
It costs (IIRC) $24.95 per rental, up to a max (I believe) of 30 days. As far as I can determine, it's full walk-away coverage like DC used to be, and it kicks in automatically whenever you use any AMEX card for the rental.
I called and they covered Ireland no problem. Italy, however, ....
