It's a long, long thread a-winding, and I'd second (third, fourth &c) many of the melodies already mentioned, and add one which I don't think has been mentioned yet, and that's "Roisin Dubh" (I notice a few mentions of O'Riada's "Mise Eire", mind you). Incidentally, "Ned of the Hill" is "Eamonn a' chnuic" (said to have been made by the man himself in the late C17th), and "Danny Boy" is "The Air from County Derry", taken down from the playing of a fiddler in Limavady in the 1850s. Add also "Ban chnuic hEireann O" ("The fair Hills of Ireland")