refreshing this thread for May Day

A music collector of the early 19th century, Edward Bunting, wrote that this song "is probably extremely ancient. It was sung by the band of Virgins that went out of Dublin to welcome the Duke of Ormond when he landed in Ireland." in 1633.

I'll be back later with information and other versions from Pádraigín Ní Uallacháin (different tunes as well, though there is one particularly well known air which, as Gypsy suggested, is often learned as air to play on an instrument).

The link given by George is to a recording by young musicians called Loch Lao and they have a sound clip at their site.

Some other sites with both lyrics and sound clips are http://home.earthlink.net/~myrrhis/thugamar.htm and http://ingeb.org/songs/thugamar.html

and this midis of ancient Irish tunes site looks interesting

Irish speakers/readers may be interested in an article in Irish Gaelic about May Day customs in the Dingle Peninsula of County Kerry
(I haven't read it yet, so can't give any summary at present)