For the past three or four years, I've made a St. Patrick's Day tradition of reading the great man's Confessio-- a text I have seen described as the beginning of Irish history, as it is the first Irish text written by an identifiable person. (I'm too lazy to verify that.)
The document is a short one and well worth reading if you want to do something genuinely appropriate to the day. St. Patrick's voice comes to us through the ages-- a humble, pious, determined, very endearing human being.
Today, I found this wonderful site, where you can read various translations of the Confessio, hear an audio version, and more! Have a look!