I have never found a recording of "7" noghts, presumably because, as noted above, the last two can be a bit bold. I have encountered several printed versions in collections from several english-speaking traditions and can attest that the song is wide-spread. The melody most commonly used is that used by the Dubliners, but there are others also. There was a story in an issue of Irish Echo last year ('98) reporting various tidbits from declassified Irish government papers (there is apparently a 25-yr suppression option) which claimed that the Irish government banned the song from air-play in Ireland at the strong urging of church authorities on the grounds that it "encouraged drunkeness and promiscuity". Most versions have the 6th night featuring variations on a visitor in the lady's bed, and the 7th night featuring a fellow caught sneaking out the door after three am. He commonly turns out to be a crown functionary of some sort. I'll be happy to send you verses I have, but I think you can pretty much let your imagination and creativity have free reign.