According to this news item in The Irish News, around 3.2 million name indexes, relating to the six counties in The Northern Ireland, Valuation Revision Books, 1864-1933 can now be accessed for free at www.ancestry.co.uk/search/collections/62658/.
The records are indexed with image links and can also be browsed. Sadly they are not dated exactly, but mostly within a range, sometimes more than ten years.
Researchers need at least a free Ancestry guest account for access.