One research area I always need clarification are land measurements in historic Ireland, prior the early 1830s, when they were replaced by the Ordnance Survey. Below you will find a list of land measurements which I consider important. While you may not come across all of them, you will encounter some along the way.
Balliboe: Used in County Tyrone, similar to a Tat[h]e. Conversion: 1 Balliboe = 80 Irish Acres.
Ballybetagh: A measurement comprising four quarters totaling about 1,000 Irish Acres.
Cartron: Equal to about 30 acres in Connacht and 60 acres in County Longford.
Carucate: The amount of land that an eight oxen team could plough in a year usually between 100 and 120 acres. It is also known as a Ploughland or Villate.
Carvagh: A measurement for acres in County Cavan.
Cunningham Acre: An Ulster measurement. It was also known as a Scottish Acre. Conversion: 1 Cunningham Acre = 1.3 English Acres.
English Acre: The standard unit for measuring land in Ireland from the 1830s.
Great Acre: A measure equal to about 20 English Acres.
Irish Acre: Common system of measuring property in Ireland from the 17th century, called a Plantation Acre. Conversion: 1 Irish Acre = 1.62 English Acre.
Poll: A measure of land equal to about 50 or 60 acres.
Sum: A division of land in Ulster known as a collop in other parts of Ireland, considered capable of supporting a family in the eighteenth and early nineteenth centuries. The measurement was based on the land necessary for a mature animal to graze.
Tat[h]e: A measurement for acres in County Fermanagh and Monaghan. Conversion: 1 Tate = 60 Irish Acres.
Towne: A local land measurement in County Antrim (also in Carlow and Offaly), equaling about 20 Great Acres.
Just be aware these other measuring systems existed alongside the English Acres through at least the early 1830s. I do see these, in records such as the Registry of Deeds, landlord estate papers and the Tithe Applotment.