The 1911 census of Ireland is one of two surviving censuses open to the public. Thanks to the National Archives of Ireland for making it available online at no cost.
In the event your Irish roots were still in Ireland at this time, genealogy buffs will find the proverbial pot of gold.
Here is the link: http://www.census.nationalarchives.ie/
Note: As my Irish luck would have it, my lines came over to the colonies much too early for this census to benefit me. Instead, we fought for the independence of America. Yep, my Irish grandpa sacrified it all as he turned against the tyranny of the English government and stepped over the line in to freedom. His Irish blood has been visible in American mayors, senators, TV (Think of Davy, the little clay guy), genealogy (the Henry System- now defunct due to advances), and countless others now in all walks of life.