Surprised no-one mentioned how it was made popular by "The Bothy Band", although Tommy Potts recorded it on his Claddagh record "The Liffey Banks". I've heard he didn't compose it outright, but re-arranged some parts of older tunes - Noel Hill once said he's heard the McDonagh brothers play parts of it years before it became popular.
An interesting comparison was pointed out to me with the melody of the Jacobite song "Come Ye O'wer Fae France" - try it yourself.
If you want a really off the wall version, listen to it by the Dutch band "Flairck" - amazing stuff.