In honor of my upcoming trip to Ireland:
Did you know that Ireland will grant U.S. citizens dual citizenship if your grandparent was born there? Anyone born outside Ireland who has a grandparent who was born in Ireland may become an Irish citizen.
You'll need some back-up records --- your grandparent's Irish birth certificate, your grandparents' marriage record and another piece of identification such as a certified death record or copy of passport, whether U.S. or Irish.
And you'll need ID too, and a form, and of course, $$$. (google "Irish dual citizenship" for exact procedures) And once that whole process is complete (can take up to a year), you can then apply for an Irish passport. Why? Because it's good throughout the whole EU - which means no long waits in the customs lines. If you travel a lot, you know what that means.
Or the nicer thought is this is a lovely way to honor your grandparent.