One of my contacts just informed me that the complete 1911 Census is now available and easily searchable at: http://www.census.nationalarchives.ie/search/
Be sure to click through to see the original handwritten census returns.
The 1901 census will be made available within a year, hopefully. All earlier censuses for Ireland were destroyed, and later censuses have not yet been released for privacy reasons.
My own great-grandfather had already emigrated to Chicago by 1911, but his sister and other relatives in Tullycorker, Tyrone appear in the census.
In the coming weeks I hope to add some posts about Cullens in the 1911 census, about things like different spellings of Cullen, Protestant Cullens, and Irish speaking Cullens.