The following is a list of relatives appearing in the 1901 census of Ireland.
Dublin
My Great Grandfather John Thomas Holmes and his brother George
http://www.census.nationalarchives.ie/pages/1901/Dublin/Rotunda/Russell_Place/1331749/
Monasterevan, Co. Kildare
His parents John & Anna Maria and sister Pamela
http://www.census.nationalarchives.ie/pages/1901/Kildare/Monasterevan/Monasterevan/1435461/
Clonsast, Co. Offaly
Anna Maria's brother Samuel Lee and family
http://www.census.nationalarchives.ie/pages/1901/King_s_Co_/Bracknagh/Clonsast_Lower/1465749/
New Ross, Co. Wexford
My Great Grandmother Albertina Zimber's two brothers and stepmother are here
http://www.census.nationalarchives.ie/pages/1901/Wexford/New_Ross_Urban/Cross_Lane/1798745/
and her uncle Richard Zimber and wife Jane
http://www.census.nationalarchives.ie/pages/1901/Wexford/New_Ross_Urban/Wexford_Street/1799501/
another uncle Lambert and aunt Rufina
http://www.census.nationalarchives.ie/pages/1901/Wexford/New_Ross_Urban/The_Quay/1799452/
Co. Waterford
My Great-Grandmother Albertina Zimber was working in Dungarvan http://www.census.nationalarchives.ie/pages/1901/Waterford/Dungarvan_No__1/Parnell_Street/1770767/
Albertina's grandfather John Daniel Ashmore and second wife
http://www.census.nationalarchives.ie/pages/1901/Waterford/Kilmeadan/Knocknacrohy/1768231/
his son James and family
http://www.census.nationalarchives.ie/pages/1901/Waterford/Portlaw/Curraghmore/1768313/
Waterford City
My Great Grandfather William O'Flaherty and his mother Mary
http://www.census.nationalarchives.ie/pages/1901/Waterford/Waterford_Urban_No__5/Gracedieu_Road/1762993/
His future wife Margaret Reale living with her brothers and sisters
http://www.census.nationalarchives.ie/pages/1901/Waterford/Waterford_Urban_No__3/Morrissons_Road/1765102/
Dublin
My grandfather Edward Kirwan with his parents and brothers and sisters
http://www.census.nationalarchives.ie/pages/1901/Dublin/Fitzwilliam/Camden_Row__South_Side_/1305619/
Nenagh, Co. Tipperary
My Great Grandfather Michael Nagle, wife Mary and family
http://www.census.nationalarchives.ie/pages/1901/Tipperary/Nenagh_West_Urban/Graces_Street/1697939/
his mother Mary Nagle and sons and daughter
http://www.census.nationalarchives.ie/pages/1901/Tipperary/Nenagh_East_Urban/Lisbunny/1697800/
My great-great-grandmother Catherine Larkin and her son
http://www.census.nationalarchives.ie/pages/1901/Tipperary/Nenagh_Rural/Gortlandroe__Part_of_/1697332/
This is as comprehensive a list as I can work out at the moment and shows the spread of ancestors across the country at the turn of the century.
