Just had a week self-catering in Ireland and the cottage had an old North Irish Roots magazine (Vol 10 No 2, 1999) with the dates when Griffiths Valuations were undertaken - not something I've seen before. Hope it's of some use to those of you with Irish ancestors! All dates obviously in the mid 1800s.
Antrim 1861/2
Armagh 64
Carlow 52/3
Cavan 56/7
Clare 55
Cork 51-3
Donegal 57
Down 63/4
Dublin 48-51
Dublin City 51
Fermanagh 62
Galway 55
Kerry 52
Kildare 51
Kilkenny 49-50
Laois (Queen's County) 58-60
Leitrim 56
Limerick 51/2
Londonderry 58/9
Longford 54
Louth 54
Mayo 56/7
Meath 55
Monaghan 58-60
Offaly (King's County) 64
Roscommon 57/8
Sligo 58
Tipperary 51
Tyrone 60
Waterford 48-51
Westmeath 54
Wexford 53
Wicklow 52/3
Antrim 1861/2
Armagh 64
Carlow 52/3
Cavan 56/7
Clare 55
Cork 51-3
Donegal 57
Down 63/4
Dublin 48-51
Dublin City 51
Fermanagh 62
Galway 55
Kerry 52
Kildare 51
Kilkenny 49-50
Laois (Queen's County) 58-60
Leitrim 56
Limerick 51/2
Londonderry 58/9
Longford 54
Louth 54
Mayo 56/7
Meath 55
Monaghan 58-60
Offaly (King's County) 64
Roscommon 57/8
Sligo 58
Tipperary 51
Tyrone 60
Waterford 48-51
Westmeath 54
Wexford 53
Wicklow 52/3