The full Griffiths Valuation can be viewed online at: http://www.askaboutireland.ie/griffith-valuation.
This web site for a family search has not only all the details of each household but also maps showing the locations of each house.
By combining the Valuation maps with modern Ordinance Survey maps, it is possible to get straight to the place where your Ireland ancestors lived in the Nineteenth Century.
There are updates to the Griffiths Valuation of Ireland ancestry and they show changes to who held the property after the initial valuation in the 1850s up to circa 1930.They are also available in PRONI in Belfast and at the Valuation Office in Dublin.
The main benefit of these maps is that, when used in conjunction with the online Griffiths Valuation index, you should be able to identify the townlands adjacent to or near to the one where you think your Ireland ancestors originated.
The 1901 and 1911 Irish census. The 1901 Census will give more data than almost any other source and the 1911 Irish census has even more data.
This was an earlier land survey carried out between 1827 and 1835,this time in order to see who should pay tithes (taxes) to the Established Church, which was the Church of Ireland (Anglican).
They can be found at the National Archives of Ireland in Dublin: http://www.nationalarchives.ie/genealogy/valuation.html
Many parishes have also been transcribed to Lindel’s website:http://freepages.genealogy.rootsweb.ancestry.com
NAI - National Archives Ireland
The National Archives of Ireland (NAI) holds a wide variety of records, many of which are relevant to an Ireland ancestry search and local history. All thirty-two counties for 1901 and 1911, searchable by all information categories, are available on their website.
Linen Hall Library Belfast
The Linen Hall Library is a truly unique institution in an Irish family tree search. Founded in 1788, it is the oldest library in Belfast and the last subscribing library in Ireland.
National Library of Ireland
The National Library of Ireland’s holdings constitute the most comprehensive collection of Irish documentary material in the world and offer an invaluable representation of Ireland’s history and heritage. Material used by family history researchers includes the microfilms of Catholic parish registers, copies of the important nineteenth century land valuations (the Tithe Applotment Books and Griffith's Valuation), trade and social directories, estate records and newspapers.
Further Recommended Reading is Tracing Your Northern Irish Ancestors by Ian Maxwell.
If you are starting an Ireland ancestry search use a Family Tree Programme to create diagrams, which act as both repositories of the data you have collected and also representations of the family links between your ancestors. http://www.genopro.com or to get started at www.ancestry.co.ukSearch Ancestry.co.uk records now!