Waking Ned Devine is a comedy set in Ireland, perfect for viewing now as St. Patrick's Day is next Wednesday. I've got a fair amount of Irish blood coursing through my veins, so anything from the Emerald Isle typically piques my interest.
I loved this nutty movie. After poor Ned Devine dies of the shock of winning the lottery, comedy ensues as several people from his village develop schemes to claim his prize. You can watch the trailer here.
Here is a list of other films set in Ireland, of which I would also recommend Dancing at Lughnasa and The Crying Game. But neither are comedies, so be warned.
If you know of another movie set in Ireland that I should see, please leave me a comment, thanks!