I agree, you donīt really have time to do much outside the airport.

That said, DUB has a great duty free. You can even do a whiskey tasting (yes, even at that hour.)

There are many FTers who like various European toiletries, and if you are one of those they are available in DUB.

The boarding process in DUB is cumbersome as you cross US immigration over there, so be aware of this if you do decide to leave the airport.