Two great surveys are the nearest thing to a census for the early-to-mid 19th century. The Tithe Applotment Books (1820s–1830s) recorded those who held agricultural land for the assessment of tithes, while Griffith's Valuation (1847–1864) listed the occupiers of property across the whole country.
Together they place families on the land townland by townland, and — read alongside maps and estate records — can pin your ancestors to a specific holding in a specific place, often where no other record survives.